That's what I meant, I should have phrased it better. It was those authors who normalised asks like this. It doesn't mean they are completely responsible for those weird anons ofc but some of those weird anons might have sent nsfw asks to those authors and they might've even responded to them. So I think it's very biased to just blame those weird anons. Like you said, best to disable anonymous asks.
I don't know about the sexual harrassment. The post didn't mention anything about recieving asks like that directed at the author. If they did, then idk why that post didn't mention it. Sexual harrassment is a very ambiguous and serious term to use in this context without any explanation.