The problem with anthropomorphic characters isn't the characters themselves, or even that they're sometimes depicted in adult ways (by which I mean, behaving like actual people would), but that a batshit minority of degenerates took advantage of the Internet to first spread and then normalize their cancerous inclinations. Which then permanently associated their particular brand of bullshit with all of the relevant media. Exactly the same as the cancerous weebs did for anime, in fact.