"body of someone who sleeps with men" is that a japanese believe or what? is that why 99% ...

"body of someone who sleeps with men" is that a japanese believe or what? is that why 99% of yaoi have this dumb stereotype of "slim, pretty dudes always takes it up in the ass"?? is it so hard to stop with all the dumb stereotypes about gay men??? just because a guy likes being fucked in the ass doesn't mean he has to look like a girl wtf is this