The elephant in the room in another world: Analyzing Isekai Tropes and how to Deconstruct them

[TGN]

Some really do just write for the money and as much as they can get before moving on to the next project...

For example the author behind Fairy Tail... knows people will buy. His popularity and career is based entirely off of knowledge he's gained about the market and he's utilized his writing skills in a way to take proper advantage of that. He has shown he can write better stories in the past, but with Fairy Tail he shows he also knows how to write to market...

That's why I say they're competent writers. Not because they're popular, not because their stories are good, but because they've clearly planned out what to write about, how to write it, and where to market it to achieve their goal. It is the intentionality behind the writing that makes it competent, not just the result.

Bro this is a thread about deconstructing anime tropes. Regardless of if the tropes represent competent writing, they're still tropes. This thread isn't about defending the 423rd story about an herbivore collecting a harem while saving the world as the stores sell meat and vegetables on a stick and nothing else.

 

[Hitspark]

Bro this is a thread about deconstructing anime tropes. Regardless of if the tropes represent competent writing, they're still tropes. This thread isn't about defending the 423rd story about an herbivore collecting a harem while saving the world as the stores sell meat and vegetables on a stick and nothing else.

A: We were having a conversation.

B: We were discussing the origin of the trope they were curious about and we got into a debate over the definition of Competency, while still discussing that trope. I don't know if you've ever had conversations before but you can speak about more than one subject matter at a time.

C: You, as well as every other person on this thread, are free to ignore any posts that you're not interested in.

And honestly the topic was dead and all parties had moved on by the time you made this reply. You're really just dragging the conversation out at this point.

 

[flannan]

= Societies not based off of fighting capabilities are corrupt.
= Only evil races build societies based off of strength, implying that human societies don't
= Human societies are therefore corrupt and easily toppled, but not evil
???

There is a difference between "personal fighting ability is rewarded" and "hierarchy is based only on fighting ability". In a healthy human kingdom, a talented knight and a talented administrator can hold the same noble title and be considered equals, because they are equally useful to the country. In an demon kingdom, administrators and generals are always strong in a 1 on 1 fight, but are often bad at their actual jobs.

Or they can do what the Mongols did. Teleport into a city, bitch slap the ruler into paying tribute, then teleport away.

You just assumed demon lords have supernaturally good logistics that would make any real-world general green with envy. Even in 21st century.

And if the demon lord is the strongest in the region, then all they'd need to do is summon their subordinates every once in a while, read their minds, and kill traitors. Not exactly the most time-consuming rule.

All of their subordinates are traitors. That's part of the job description, when the only thing holding the country together is "weak should obey the strong".

But the heroes should already be king. In Isekai Smartphone, the emperor of the neighboring empire got rekt by their own general. Sure, that general got some buffs (that the emperor definitely should have gotten already), but you'd think there'd be more of a fight. The kings should be among the most powerful in the nation, instead they're so often puppets just waiting for a hero to arrive. And when the kings do seem to be powerful, they're only used in one-off situations, never an actual consideration.

I think you'll do well in a demon kingdom.
In case of Isekai Smartphone, the general got his hands on 2 epic artifacts not normally available even to kings. And the emperor was old anyway.

 

[TGN]

In a healthy human kingdom, a talented knight and a talented administrator can hold the same noble title and be considered equals, because they are equally useful to the country.

Societies that do not reward people of extraordinary power are portrayed as corrupt and quickly topped by enemies, external or internal.

Historically speaking, human kingdoms are rarely healthy and are often lead by incompetent rulers, especially absolute monarchies. Say some super powerful dude takes over an empire, and his dynasty retains his strength. What stops that system from spreading to all other kingdoms? Talented administrators can do little against a guy who just blows up the capital of the nations he conquers. Thus, all other nations must either follow suit or be conquered. Unlike in 18th century France, the peasants of such nations have no physical advantage over the monarchs, so there is no reason for talented administrators to be vital to the existence of a monarchy, nor for them holding noble titles.

You just assumed demon lords have supernaturally good logistics that would make any real-world general green with envy. Even in 21st century.

I think being able to teleport miles away at a time and travel at nearly the speed of sound would allow for supernaturally good logistics. Especially when your army consists of a single person.

All of their subordinates are traitors. That's part of the job description, when the only thing holding the country together is "weak should obey the strong".

By traitors I mean those actively conspiring against the demon lord. I'm sure most people would be kept in check if the demon lord can just snap them out of existence.

In case of Isekai Smartphone, the general got his hands on 2 epic artifacts not normally available even to kings.

It's quite the coincidence that our protagonist just happened to be in the right place at the right time. Those artifacts should have long since been found and worked their way up to the king. Why did none of the other monarchies seem to have any artifacts whatsoever, yet artifacts had been falling out of the sky for what could be centuries?

 

[flannan]

It's quite the coincidence that our protagonist just happened to be in the right place at the right time. Those artifacts should have long since been found and worked their way up to the king. Why did none of the other monarchies seem to have any artifacts whatsoever, yet artifacts had been falling out of the sky for what could be centuries?

The previous season had another artifact from that set. The owner almost conquered presudo-Japan.
As for coincidence, that's the name of the game in Isekai Smartphone. There is a great amount of coincidences, both for the good guys and for the bad guys.

I will respond about the rest later.

 

[TGN]

The previous season had another artifact from that set. The owner almost conquered presudo-Japan.

And if all it takes is some rare artifact to conquer pseudo-Japan, why has no one else done it? This surely can't be the first time an artifact fell.

As for coincidence, that's the name of the game in Isekai Smartphone.

And most Isekai, apparently.

 

[GipoScribantino]

And most Isekai, apparently.

In fairness towards isekai, a lot of good fiction relies on coincidences too. It depends on how heavily the story relies on it and how much it holds on when questioned.

To make an example using one of my most disliked works, in Arifureta when at the beginning the MC runs away from the monster by digging a wall, it is quite the coincidence that he found a magic stone that gives him power by drinking the dripping water; however, it makes sense that hidden in a wall of the deepest layer of a dungeon a magic stone like that can develop and the suspension of disbelief can still hold.
On the other hand, in Garbage Brave, which is essentially a clone of Arifureta, the fact that "dismantle" works on living being and it's an insta-kill is certainly a coincidence nobody ever noticed; truly, for a job that is a natural occurrence in the world the story is settled in, for nobody to notice this detail in the millennia the human race has been alive, that surely is a coincidence. As you can see from my sarcasm, here it is difficult to justify this coincidence unless you willingly ignore the plot holes, so if you add the other unintetesting elements the story is made of, you get the usual poorly written isekai deus ex machina.

Indeed, it might be intetesting to open another thread to not just analyze the "what a coincidence!" moments in isekai but to also think of how the story coukd be written to not rely on those coincidences. It might enlighten us on how many of those isekai could actually have a story progression at all if there were no (or at least fewer) dei ex machina.

 

[flannan]

And if all it takes is some rare artifact to conquer pseudo-Japan, why has no one else done it? This surely can't be the first time an artifact fell.

These artifacts are that rare. Also, they don't come with an instruction manual. And most of them do not protect the wearer from assassination (which is what happened to the would-be conqueror). So, it takes some talent, cunning and position to make good use of them.
For example, the general's bracers are pretty powerful, but without demon lord contract protecting him from magic, he would be easily defeated by magic. And the general could only organize a demon lord contract using his position as a general (and even he risked losing that position if discovered).

And most Isekai, apparently.

Isekai Smartphone stuck me as using coincidences much more often than comparable works. For example, in this season's Tensei Kizoku, there was exactly one coincidence - where MC got to rescue a princess and she fell in love with him, setting MC on a path of aristocratic intrigue instead of commoner adventuring. Everything else flows naturally from there.

Historically speaking, human kingdoms are rarely healthy and are often lead by incompetent rulers, especially absolute monarchies. Say some super powerful dude takes over an empire, and his dynasty retains his strength. What stops that system from spreading to all other kingdoms? Talented administrators can do little against a guy who just blows up the capital of the nations he conquers. Thus, all other nations must either follow suit or be conquered. Unlike in 18th century France, the peasants of such nations have no physical advantage over the monarchs, so there is no reason for talented administrators to be vital to the existence of a monarchy, nor for them holding noble titles.

You clearly do not understand the strength of talented administrators. They are people who can run a kingdom that's worth protecting. Strength of a talented knight might be inferior to strength of a demon lord. But strength of a talented knight plus love for the Motherland is much stronger than any demon lord. Especially if you can get a team of 5 knights against any demon lord.
Can't forget the usefulness of fantasy technology. Fantasy smiths can't produce The Sword of Light, but they can still make quite potent weapons - if you can afford to get them good materials. And fantasy mages can produce city-protecting force fields against demon lords who attempt to nuke your capital.
But in the end, strength is not reliably heritable in fantasy. So short-lived races need a lot of common people to find talented warriors from there, and to promote them to knights who will defend the kingdom. And that is only possible with talented administration.

I think being able to teleport miles away at a time and travel at nearly the speed of sound would allow for supernaturally good logistics. Especially when your army consists of a single person.

Exactly. You're making an assumption about the workings of magic that would destroy medieval fantasy if applied consistently. Even renaissance fantasy would have problems.
This assumption, together with nuking cities, gets us to post-WWII world, where Mutually Assured Destruction reigns supreme. The world might still have medieval trappings, but its politics and economics cannot stay medieval.
To retain Renaissance-level politics and economics common to Japanese fantasy, teleportation has to be pushed to the difficulty level available only to archmages who don't need anything from humans anymore.

 

[TGN]

In fairness towards isekai, a lot of good fiction relies on coincidences too. It depends on how heavily the story relies on it and how much it holds on when questioned.

Yeah, coincidences are permissible if there was sufficient build-up to them, if there was previous writing that set them up. In most Isekai, coincidences are substitutes for good writing, hence my comment.

Indeed, it might be intetesting to open another thread to not just analyze the "what a coincidence!" moments in isekai but to also think of how the story coukd be written to not rely on those coincidences.

Coincidences are part of every day life. To write a fiction devoid of them is to have a purely if/then sequential time line.

 

[TGN]

These artifacts are that rare. Also, they don't come with an instruction manual. And most of them do not protect the wearer from assassination (which is what happened to the would-be conqueror). So, it takes some talent, cunning and position to make good use of them.

That only makes it more unbelievable that MC-kun came across the general mere minutes after he rebelled.

Isekai Smartphone stuck me as using coincidences much more often than comparable works. For example, in this season's Tensei Kizoku, there was exactly one coincidence - where MC got to rescue a princess and she fell in love with him, setting MC on a path of aristocratic intrigue instead of commoner adventuring. Everything else flows naturally from there.

Another coincidence is that MC-kun came across a robber who would have fucking tripped on his own, which is what allowed him to be isekaied in the first place. Another is that his sister and catgirl maid happened to be strolling at the back of the mansion in the middle of the night when he summoned his Minotaur thing. And that's just in the first episode. Other Isekai are more rife with coincidences, like the Cheat Skill Isekai that's airing right now.

Especially if you can get a team of 5 knights against any demon lord.

Implying the demon lord will allow five knights to organize to oppose him, which would be pretty difficult to do if the demon lord teleported around razing cities, or at least not doing nothing.

And fantasy mages can produce city-protecting force fields against demon lords who attempt to nuke your capital.

Force fields which oh so rarely are actually present in cities and which are extremely vulnerable to sieges, such as nuking the surrounding area and cutting off food/water supplies.

But in the end, strength is not reliably heritable in fantasy. So short-lived races need a lot of common people to find talented warriors from there, and to promote them to knights who will defend the kingdom. And that is only possible with talented administration.

Theoretically, that system could work (similar to the Ottoman Janissaries). In the world of most Isekai, it would collapse. Either due to the existence of a demon lord who just conquers the whole thing, or abnormally powerful people popping up like Wack-a-Mole.

You're making an assumption about the workings of magic that would destroy medieval fantasy if applied consistently.

I thought demon lords and other powerful entities tend to have the ability to teleport to the main character, beat them up, then disappear back to their castles when plot needed them to. Even then, riding a dragon seems to get one across the world in a few days' time.

...teleportation has to be pushed to the difficulty level available only to archmages who don't need anything from humans anymore.

Most Isekai don't push teleportation or other high mobility magics to that extreme. In most Isekai, archmages still like conquest. InVermeil In Gold (not an Isekai, but a similar fantasy), there's an organization of powerful people who seem like they want to conquer the world, and who are nigh unmatchable. Though archmages need not seek human destruction to do so. Like how humans treat Earth, archmages could destroy empires purely as a side-effect of their research.

 

[GipoScribantino]

Coincidences are part of every day life. To write a fiction devoid of them is to have a purely if/then sequential time line.

For the sake of clarity, I want to specify that I did not mean to remove all coincidences. I meant as taking some of them, especially the poorly executed ones, and see what can be done without them.

Taking Garbage Brave again for example, what if "dismantle" did not work on still-living beings? How could have the author pull off a victory of the MC against the very first monster he met? Maybe dismantle could have created a pitfall imprisoning the monster? Maybe something else?
This kind of stuff, not an all-or-nothing.

 

[flannan]

That only makes it more unbelievable that MC-kun came across the general mere minutes after he rebelled.

Like I have said, Isekai Smartphone uses a lot of coincidences.

Another coincidence is that MC-kun came across a robber who would have fucking tripped on his own, which is what allowed him to be isekaied in the first place. Another is that his sister and catgirl maid happened to be strolling at the back of the mansion in the middle of the night when he summoned his Minotaur thing.

Circumstances of death are not coincidence. They are premise. And there are only so many ways to die young in peaceful Japan - either by random criminal violence, or in a traffic accident, or from some incurable disease. That last one is rarely used, but Leadale had it.
The others are not coincidences, because they do not give MC any kind of advantage. That's just character reuse, a common technique in writing.

I thought demon lords and other powerful entities tend to have the ability to teleport to the main character, beat them up, then disappear back to their castles when plot needed them to.

Yeah. And then the hero will have to walk for 6 volumes to get to the castle. While the demon lord does absolutely nothing.
This suggests that either the demon lord teleportation has hidden restrictions, or the demon lord is an archmage/spirit beyond the level where he needs the world (and he is just organizing an elaborate suicide).

 

[flannan]

Most Isekai don't push teleportation or other high mobility magics to that extreme. In most Isekai, archmages still like conquest. InVermeil In Gold (not an Isekai, but a similar fantasy), there's an organization of powerful people who seem like they want to conquer the world, and who are nigh unmatchable.

And so, we're clearly breaking up with medieval fantasy, and getting to around 19th century levels of society, where academies attempt to mass-produce powerful mages, enabling society to counter most rogue elements.

Though archmages need not seek human destruction to do so. Like how humans treat Earth, archmages could destroy empires purely as a side-effect of their research.

That is something I'd like to see in fantasy someday.

 

[TGN]

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[TGN]

The others are not coincidences, because they do not give MC any kind of advantage.

They're still coincidences, just ones not meaningful to the plot

This suggests that either the demon lord teleportation has hidden restrictions, or the demon lord is an archmage/spirit beyond the level where he needs the world

Or that the writers are trapped in RPG story lines and haven't thought about having the demon lord actually do something

And so, we're clearly breaking up with medieval fantasy, and getting to around 19th century levels of society, where academies attempt to mass-produce powerful mages, enabling society to counter most rogue elements.

I'm not exactly sure what your point is here. The magic to do this present in most anime. Writers just don't have the want to actually explore these advancements. Dividing these fictional worlds into time frames like medieval doesn't work since magic breaks the traditional time frames that humans divide ourselves into.

 

[flannan]

Dividing these fictional worlds into time frames like medieval doesn't work since magic breaks the traditional time frames that humans divide ourselves into.

On the contrary. If you get out of more-or-less real historical periods (or at least established genres), you lose relatability and recognition, and are now stuck with having to do an excessive amount of worldbuilding, turning your work into sci-fi exploration of the setting, regardless of what you wanted to do originally.

 

[TGN]

On the contrary. If you get out of more-or-less real historical periods (or at least established genres), you lose relatability and recognition, and are now stuck with having to do an excessive amount of worldbuilding, turning your work into sci-fi exploration of the setting, regardless of what you wanted to do originally.

There are no excuses in a deconstruction. Useful as these tropes may be, they are still tropes with no legs to stand on. I mean, these nations have an emperor with absolute, divine-right rule and yet feudalism still seems to be going strong. Even worse, guilds are ever-present, despite them only arising in part due to the decline of the nobles. These worlds make no sense, and almost never do authors try to examine these worlds and make something unique and that isn't a carbon copy of the same beaten-to-death settings. They could at least copy Japanese feudalism, which arose concurrently but independently of European feudalism. But Europe is used for fantasy while Japan is left as history.

 

[TGN]

Since I've been having to look at fantasy worlds more closely, I'll discuss some more magics that I've always felt was underused.

1: Cleaning magic. We all know how this works, some dude sees a dirty building and, saying the magic words, all the dust disappears and everything is repaired. But what does it mean to clean dust? Where does it go? How is only the dust removed? If someone used cleaning magic on a person, what happens? It would be a powerful combat magic if it could 'clean' the person of their blood. Redo of Healer does something similar with healing magic. It would also be pretty useful healing magic if it could clean bacteria. And don't get me started on the 'repairing objects' bit.

2: Storage magic. Again, this is used only for its namesake purpose and nothing else. The Fate series has two great examples of this being used offensively, storing weapons and flinging at opponents. The JJBA stands Cream and The Hand are also examples of offensive uses, moving the openings around and eating whatever stands in its way. The openings may also be used as shields, blocking perhaps any attack. Another aspect of storage magic is that living things are usually unable to be stored. Does that include bacteria? Then it could sterilize medical equipment or food and make them safer to use/eat. Foods also can usually be stored indefinitely and never spoil, implying time is frozen. There's no real reason why living things can't be stored. Could this allow for the preservation of organism through time, of sun-kings and intellectuals storing themselves when needed to rule their kingdoms in times of strife? Allowing the storage of living things also opens up the ability of secret moving homes and villages. Tsukimichi played around with this concept. An anime which takes this to the extreme of there being dozens to hundreds of houses, villages, and even cities moving around in other dimensional portals could have an interesting concept.

3: Psychological magic. I've touched on this before, that this magic is practically untouched. For example, ep3 of Tensei Kizoku had 'calming magic'. Imagine the combat potential. Calming an opponent down to the point that they aren't in the mindset to fight. Calming allies to help them think more rationally and deliberately. Imagine the therapeutic uses. Imagine the control this gives, someone selling hits of this magic like a drug. In ep2 of Shijō Saikyō no Daimaō, succubi have great aptitude for magic. So essentially like a human, but better. How original. Perhaps succubi could instead specialize in psychological attacks. Have them fill their opponents with extreme rage, unnecessary caution or recklessness, or crippling depression. Make them unable to fight with volatile emotions. That would be an interesting take on the idea. And they can also increase people's libido, because succubus. I'd rant a bit longer, but it's getting late and I'm too tired.

 

[flannan]

Since I've been having to look at fantasy worlds more closely, I'll discuss some more magics that I've always felt was underused.

1: Cleaning magic. We all know how this works, some dude sees a dirty building and, saying the magic words, all the dust disappears and everything is repaired. But what does it mean to clean dust? Where does it go? How is only the dust removed? If someone used cleaning magic on a person, what happens? It would be a powerful combat magic if it could 'clean' the person of their blood. Redo of Healer does something similar with healing magic. It would also be pretty useful healing magic if it could clean bacteria. And don't get me started on the 'repairing objects' bit.

2: Storage magic. Again, this is used only for its namesake purpose and nothing else. The Fate series has two great examples of this being used offensively, storing weapons and flinging at opponents. The JJBA stands Cream and The Hand are also examples of offensive uses, moving the openings around and eating whatever stands in its way. The openings may also be used as shields, blocking perhaps any attack. Another aspect of storage magic is that living things are usually unable to be stored. Does that include bacteria? Then it could sterilize medical equipment or food and make them safer to use/eat. Foods also can usually be stored indefinitely and never spoil, implying time is frozen. There's no real reason why living things can't be stored. Could this allow for the preservation of organism through time, of sun-kings and intellectuals storing themselves when needed to rule their kingdoms in times of strife? Allowing the storage of living things also opens up the ability of secret moving homes and villages. Tsukimichi played around with this concept. An anime which takes this to the extreme of there being dozens to hundreds of houses, villages, and even cities moving around in other dimensional portals could have an interesting concept.

3: Psychological magic. I've touched on this before, that this magic is practically untouched. For example, ep3 of Tensei Kizoku had 'calming magic'. Imagine the combat potential. Calming an opponent down to the point that they aren't in the mindset to fight. Calming allies to help them think more rationally and deliberately. Imagine the therapeutic uses. Imagine the control this gives, someone selling hits of this magic like a drug. In ep2 of Shijō Saikyō no Daimaō, succubi have great aptitude for magic. So essentially like a human, but better. How original. Perhaps succubi could instead specialize in psychological attacks. Have them fill their opponents with extreme rage, unnecessary caution or recklessness, or crippling depression. Make them unable to fight with volatile emotions. That would be an interesting take on the idea. And they can also increase people's libido, because succubus. I'd rant a bit longer, but it's getting late and I'm too tired.

First, while direct magic (such as "cleaning" people of blood or storing them in storage magic might seem useful, it should definitely be resistible, regardless of what the original was like. Spells not intended as offensive spells can be assumed to be very easily resistible, with them hurting people only as often as industrial or household machinery of the real world. I guess using them in battle is the equivalent of bringing a chainsaw to a shootout.
Second, you're on a manga site. And the thing about manga is, "save-or-die" spells don't look good there. Which is why in visual media, mages rely on projectile spells. Shiny, big, highly visible projectile spells.
Third, the same applies to psychological magic.
Fourth, I've seen examples of pretty much everything you mentioned.

Now for specifics:
1. Cleaning magic is usually seen as a "holy" attribute spell. I even saw a setting where clerics refuse to use it for mundane cleaning, and insist on only using it for purification of evil. Thus, it is not a morally-neutral force you can abuse. But it does clean bacteria and is part of every healer's arsenal. Yes, it can repair objects, because "holy" magic can repair everything, even people.
2. Storage magic where living things can be stored is usually seen as a higher-level version. For example, Man Picked Up by the Gods had to learn "dimensional home" to carry his ooze of slimes with him. Such spells are usually seen at the archmage level, and a village that moves around in one would be the comically overpowered village.
People who want to be preserved for the future have many other options. Such as ascending into a long-lived creature like an angel or a lich. Or getting sealed. Or using reincarnation magic.
Using storage magic for sterilization is the only part that's interesting. Assuming viruses count as living things for the purpose of this magic (in the real world, they're kind of on the border between living and nonliving). But cleaning magic is usually portrayed as easier and in the same school as healing, so healers will probably rely on that.
3. Psychological magic is really just a reflavor of psychic powers normally found in modern and sci-fi settings. There is nothing left to explore here.
Succubi in Shijou Saikou no Daimaou have great aptitude for magic and are also perverts who misuse magic out of their own will. And I like this interpretation more.

 

[GipoScribantino]

There's a trope that by itself wouldn't be an issue as I will show later, but due to its poor execution pretty much everywhere I think it fits an analysis in this thread: the "long-range party members have low defense" trope.

Here I will focus only on spellcasters (mages, priests, etc.) as archers and other weapon users are generally not treated as poorly as magic units.

It is painfully obvious that most isekai authors have dealt with fantasy settings only through RPG games (or other isekai works, but all the genre-defining works are based on games); in there, due to the very nature of magic having more effects than normal attacks, magic-oriented units have to be balanced in order not to make the game too easy and thus boring (or too unforgiving for people who don't want to play a mage e.g. in MMOs). As such, these units must have low physical attack and defense so that if you do not have some other unit who can protect them (a tank getting targeted by enemies intentionally, a knight with the passive "protect units with low health" skill, etc.) they die in one hit and if they run out of MP they become mostly useless, preventing you from spamming high power spells without a strategy.
Of course some games have other ways to make them more resilient on their own (e.g. mastering classes in Final Fantasy V also boosts stats), but in general they are physically weak for balancing purposes.

Bcause in the world of isekai works the people are not game characters but "real life" people, even when the isekai is based on a game, this whole "balancing" nonsense does not apply. Fighting, be it against a monster or another human during a war, is a matter of survival and everybody involved want people to not die: the soldier because, well, he dies if he is killed; the noble that waged war because recovering the lost soldiers, especially the veterans, is more expensive compared to the normal conscription cycle especially during a war.

Despite that, though, authors have these mages with almost no clothing on to the point of pretty much getting killed in one hit by a random attack.

The issue here is that authors never explain why can't mages put on some heavy armor to protect themselves. Mages never need mobility, in fact when casting they almost always need to stand still and basically be an open target waiting to be attacked, so wearing a resistant heavy armor would be the correct choice. It is somewhat assumed that mages can't wear any armor without ever going into details.
The "no physical strength" excuse doesn't really make sense: a real person not bound by game rules for balancing can just hit the gym, especially if they are adventurers or soldiers, and get enough muscles to be magic-shooting tanks. Even if magic were to require reading books all day every day, they can still do that while lifting. Multitasking is a real thing despite what isekai authors think.

The ironic part here is that there is at least one valid reason to explain why mages can't wear armors and the worst part is that this reason can be explained in less words than the whole adventurer ranks business that authors always go into a lot of details that almost always never matter.
The reason is: "magic can't circulate if equipment is too heavy".
Think of it like wearing layered clothes during cold winter days: the body heat is contained by the clothes so you keep warm; similarly a heavy equipment would prevent the magic power from interacting with the atmosphere and it would decrease the spell effectiveness.
That would excuse mages in their almost-nudity or whatever other zero-defence clothes they wear.

TL;DR: authors assume mages work like game characters even when it wouldn't make sense and even though there are perfectly fine explanations for that, they never explain anything despite going into the finest details on useless things.