I'm not sure. I'll admit I'm not really into tumblr/twitter fandom, so I can't speak with too much authority, but I imagine it doesn't help that fandom's kind of become mainstream, and sadly there are a lot of people who still hold socially conservative values. So they want to do fandom, but want to do it "in line" with their views.

Again, I've seen it before - when I was in the Harry Potter fandom, there were a LOT of religious conservatives running around. But they tended to get shot down pretty quickly - rightfully so. At least where I went, apparently there were bigoted fan spaces, which saddens me a lot.