It's not going to go away. And hating on it won't make it any less annoying.
..then don't hate on it? lol
I've never minded this fandom for a long time, until I started seeing it literally everywhere and it became over bearingly obnoxious. I find it on TF2, Blockland, Flash websites, image boards, forums, and various artboards I like to frequent. While some fandoms are present in multiple sites, no other fandom has spread this damn far.
The reason it grew so large is because of, entertainingly enough,
how much people bash it, in conjunction with the vast improvement in communication over the years. Star Trek had a
huge following (and still does), and they got made fun of for it to some degree, but there wasn't much way of spreading it around compared to modern days; now that everyone is connected to everyone else almost 24/7 things spread much faster.
So people spread this idea about the show, that it's good, and people can't believe it! A show aimed at children enjoyable by adults? So they try it out and some actually like it (believe it or not, some of us are actually enjoying ourselves and not in it for the irony). Then everyone else can't believe how stupid it is, so they tell their friends, and some of their friends try it out, and a few of them like it too, and it just keeps going. It could have very well happened with anything, but someone decided My Little Pony was what it would be, and so it was.
People always say that "these are just the extreme ones" but why is it the extreme ones are the only ones anyone can ever find?
Be it on the forum, in media, or just people you meet online. Always. Alwayyys. The people who claim to not be the extreme bronies are always just conveniently the ones defending it when content like this surfaces.
Because the extreme ones aren't ashamed, and the non-extreme ones are ashamed
for them.