I think what’s happening is that they tell themselves that the show isn’t “glorifying” or “romanticizing” it, whether or not that’s true; meanwhile they believe any fanfiction of the same topics is automatically supporting those themes irl.

I feel like you can see some of this happening with HotD, where antis ARE turning on it more, because its pretty hard to argue that the incest isn’t being romanticized to hell and back.