So, I looked through the thread
@Halo posted and I have some thoughts. There seemed to be a prevailing feel that the tag of bara/gei-komi was too niche and as such did not serve a purpose. And also people felt that the arguments put forth were overly emotional and lacking in legitimate substance.
So I guess I'll pivot and give my best argument for why bara/gei-komi should be a tag. Even though realistically I just want to slap a LGBT tag on anything yuri, yaoi, shounen ai, shoujo ai, crossdressing, or gender swap. And then I would like to have crossdressing or genderswap removed (provided there legitimately is no crossdressing or gender swapping through magical means as most gender swap manga are). Although I still feel like this is something that would be useful for sorting manga, I see that it probably won't be implemented and there seems to be a general disinterest (and animosity from a vocal yet minority posting group).
So, here's my argument.
Villainess, Medical, Virtual Reality, Philosophical, Monster Girl, Gyaru, Traditional Games
133, 136, 207, 98, 314, 255, 51+23+41+9+158 (I've combined the genre that seem most like Traditional Games on mangaupdates. This may be an overestimate due to overlap), 393
These numbers are the corresponding usage stats for each of these genres, all of which are implemented by mangadex currently. All except for the last at 393, which if you're a clever reader you might guess is the usage value for bara. As a genre it is bigger than all five of these already implemented tags. And some of them for one of them it is three times as popular. I like all of these implemented tags, so I wouldn't argue that you remove them, but I would argue that if they are worthy of inclusion, bara, which is distinct in content from yaoi should remain.
Another prevailing argument is that tag distinction is difficult for bara. How am I supposed to tell two different gay manga apart? Well, if they're hairy, muscly, and masculine, it's probably bara. If they have hands bigger than their faces and could pass as women in mail uniforms, it's probably yaoi.
This also doesn't seem to be too serious an issue for the many many other vague or poorly defined tags. Philosophical? What exactly does that mean? A manga about selling your life for money, yeah I could see how that's philosophical (I guess, idk was pretty melodramatic and light on actual meaning). A story about a teacher literally teaching about ethics in a school setting. Yeah, that sounds like something to do with philosophy. A fan doujin about Osomatsu-san joining the mafia, apparently that's also tagged philosophical?
Yet somehow neither of the two versions nor the doujin for Kino no Tabi are listed currently under philosophical despite the fact that the slogan is "The world is not beautiful, therefore it is" a statement which is pretty much a philosophy onto itself. Every chapter is specifically a vignette with some philosophical, political, or other meaning. One of my favorites personally is the three day stay in a town suffering under the tyranny of the majority, something I feel might be contextually relevant currently. And even if it is similar, there are multiple tags that serve similar purposes. Samurai and historical, monster and monster girl, horror and psychological and thriller, harem and reverse harem,
Another argument I saw was that Dynasty Scans filled this role already. Dynasty Scans hosts primarily yuri, and even if they did fill this role I still think including tags like this is generally a good idea. Why specifically drive away one demographic? If there were specifically websites designed for other niche manga would we remove tags for those categories? Since yuri is so soundly handled elsewhere why even have a yuri tag or host it?
Another point brought up is that you could sort by seinen + yaoi. This ignores the fact that most manga on this website doesn't actually include a demographic tag and the work to add a demographic tag to every piece of yaoi is in my opinion probably close to on par with the amount of work to start using a bara tag. Not to mention that bara is often mislabeled as josei instead of seinen. Take for example
https://mangadex.org/title/38936/senya-ichiya-shitone-no-himegoto
https://mangadex.org/title/38937/tango-no-otoko
both currently marked josei on mangadex and seinen on mangaupdates.
Another argument I saw which I was quite confused and almost concerned about was that LGBT content is "catered for" it undermines the greater LGBT movement. I wholeheartedly disagree. When LGBT content is accepted as normal it generally has the opposite affect and tends to make people less bigoted. That's why so many people clamor for representation in media. They want their demographic to be viewed as a normal facet of society.
Finally there's the recursive argument. "I don't see demand for it here, so it's a bad idea". I'd like to summarize why this is a poor argument with an allegorical story. There is a farmer sitting atop the perfect soil to grow the most expensive crop possible, the soil is alright at growing the cheapest (yet relatively easy to grow crop). Every time the more lucrative crop sprouts it is weeded out for fear of it competing with his current harvest without bearing fruit. When asked why he doesn't try growing the more lucrative plant, he responds by stating
"If the soil was good for it, then it should grow on it's own".
The farmer does not realize that by actively inhibiting it's growth he has created a self actualizing statement. He does not think it's viable, so he is actively hindering it, which in tern validates his belief. By ignoring a demographic you are implicitly telling them "do not come here". Tags relating to trans or bara manga have been requested for realistically 3+ years now, and people will continue to suggest them. (Personally I think that if moderation is so intent on not utilizing tags like this they should be listed under the planned and rejected features thread. Seeing as forum posts are not currently able to be searched natively yet, it is likely people will ask for this feature again).
But basically, what I'm getting at is that we're fostering a community actively uninviting to the gay male demographic, and then justifying it by pointing out they're not here. Which seems like the obvious consequence.
In summary, I think we should add either bara or gei-komi as tags. Preferably gei-komi as it doesn't have a pejorative connotation in Japan and it also sounds cooler.