I will point out a few things.
BL as a category on Tapas only exists because other writers complained that it was drowning out the other genres.
GL wanted to exist for easy accessibility like BL. LGBT+ creators wanted an LGBT+ category to distinguish their stories from what is expected from BL and GL. (Because like KR explained these are well defined categories that have existed for decades---and like most categorization in publishing comes some expectations. LGBT+ novels that don't adhere to them will have a hard time trying to sell as them.)
Distilling arrangements is something that happens to HELP readers find the books they want to read and reduce competition. "Werewolf" and "Vampire" are not genres but sub categories of paranormal creatures. They are stated as genres on Wattpad so that they don't flood the paranormal and fantasy categories and make it hard for other creators.
LGBT+ literature, mind you, is also a well defined sub-genre and genre in publishing.
I will point something out.
As you complain about all the new genres that don't need to exist I assure you that you would have been one of the people complaining when BL flooded every genre.
Introduction of the new genres only does a few things: It helps readers navigate better, and it gives writers a better chance at getting discovered.
How you can make this into a bad thing is quite impressive I'm not going to lie.