Mm, I didn't explain it very well. "Attractive" is a good/bad measure though (subjective, yes, but that's what I was talking about with that example)

What I was thinking about was slash writers: wanting to write romances/porn where the main characters are male (and young etc) is perfectly reasonable if that's what you find attractive. But using that as an excuse to marginalise/demonise etc all the female characters (and some do) is sexist, and since female characters tend to get marginalised/demonised in regular fiction too it doesn't leave many spaces for them to be treated well.