I understand all that (lots and lots of cartoons aimed at children have bits added to make the parents watching the show with their kids laugh), and I still think it would be weird if adult males worshiped at the alter of any of those things.
I never watched My Little Pony, though disgracefully I've seen photos of dead horses. Yes, this worship can look weird and bizarre - just like the Atlas Forum and the county swing maps, on the other hand. I don't care if this is an offence for the MLP fans, but for sure that 'adult male' reference is a bit sexist. Are women supposed to be more infantile than men? In that case I prefer gals and... bronies.
Nevertheless, it's a cult that takes itself seriously. Like men trapped inside womens' bodies or something.
Seriously ? Just f** off dude. It is a f***ing cartoon. Some of us like it, some of us love it, I know I'm not getting dressed as a pony and going around like that, and even those who do, they do it, no harm done, what the hell ! It's like you are afraid of something you don't understand. Some of us are taking this more seriously than others, but anyway a lot of people take a lot of things seriously. Maybe you have a favorite sports team, or band or whatever. This is no different. And anyway MLP is not my favorite show ever. It's just one of the shows I watch because I like it, it soothes me, but I also watch Dexter or Modern Family. We are not freaks. Stop believing that just because you don't get it.
As to men trapped inside womens' bodies, well that is a real psychological and medical issue, and the symptoms are generally a bit more serious than just watching MLP. And you don't get to make fun of these people either, these people need compassion, help, like people in wheelchairs. What kind of person are you ?
In this case I can detect some lack of empathy towards women trapped in men's bodies. Hey, it's a good thing when someone points that certain opinions are sexist and not too kind with women. These particular cases of crossed gender identity and the like are even worse treated. Try to understand, this is not a case of political correctness but a case of humanity, even when we're talking about people who doesn't need a wheelchair. As for the rest of the post Zanas answered well.