@Glomoro @Kizuro the thing with this manga is that Japanese/Korean/Chinese RPG are designed very differently from Western RPG. If you have ever played any of those you'll see end game raid/dungeon LFG always have a specific class they're looking for.
The thing is, this system is not a good thing in competitive PvP environment due to the salty nature, if someone fucks up once, people are less likely to just "don't mind" and try again (I mean you can't even try again if you lose), I hated how modern moba relies too much on this system and design the characters specifically for a single role.
Back in the Dota (OG) days the concept of Tank/DPS/Support was not an offical thing but more of players figuring it out themselves.
For example a STR hero gets bonus damage from STR items, but since those stats also increase their HP they "naturally" becomes a tank, an AGI hero can "naturally" be a DPS because building AGI will increase both their damage and attack speed, but there's some STR type hero with high damage skills, but high mana cost and low MP pool, so they build INT/STR hybrid items to compensate and becomes a caster.