Fujo here. Do you really think we care about how realistic yaoi is to irl fags? Do you maybe want us to include descriptions of poopoo too?
It's a media made for women and by women. Lots of works (omegaverse for example) literally make bottoms to be fertile, with wombs and breasts. The only "male" left is visual. Since fujos are fat and ugly, it's depressing to read love stories about dreamy men fucking thin, cute girls. But other males are not seen as rivals, so in yaoi you get het relationship without being reminded what a failure of a woman you are.
However, pooners love poisoning fanfiction well with their inclusive trans stories, which are very annoying, as it turns yaoi into het with an ugly girl on T.