One little faction takes over, because they're the loudest and the most obnoxious. And it just-so-happens that they hate the very thing they're supposed to be fans of.
And they take over a site like Tumblr all to themselves, and make it seem like EVERYONE in the fandom agrees with them, when we so don't, and in fact probably not many actually agree with them at all. They're just the loudest, the most obnoxious.
Why is that? Because the rest of us are too nice, we don't want to cause offense or get into stupid flame wars, because believe me these people are ready to go to freaking war. They're ready to take it too far, and the rest of us kinda have other things to do.
No one has to like everything. But when it gets to the point where you're HATING this thing, then why still be in the fandom? At the point where you're not having fun, where it isn't for you, it's time to uh... (sorry)... Let it go.
This applies to so many fandoms, and it's why I can never really take part, I just sit on the sidelines wondering what all the hate and angst is about, while biting my lip about this or that misunderstood thing, knowing I can never speak up without incurring The Wrath. Occasionally I have friends or family that I can geek-out with, but really I can only just be on the outside-looking-in of any fandom.
Fandoms suck because one little group can take it over, and make you feel like you're wrong for liking this thing you're a fan of. Like you're the one doing it wrong. It's them doing it wrong.