I think it was just by chance. It's the fandom that then created more fandom and so on. For me the fandom made the difference. If there wasn't this big brony fandom I'd probably never given it a try. Also the huge amount of good qualitiy fan videos made the difference for me.V8 Ninja said:My problem with My Little Pony is that it's insanely popular when there are better kids cartoons out there. I mean, look at something like Adventure Time or Regular Show. Both of those shows are by far better executed than MLP and they aren't as "preachy" as MLP. They also can appeal to more than just kids, which MLP aimed for exclusively but also somehow hit the 4chan demographic.
It could have happend with any show. It were probably multible little factors that led to MLP specifically but that would require lots of research and detail analysis.
Alfred J. quack [http://en.m.wikipedia.org/wiki/Alfred_J._Kwak] is a good example of a Show that would deserve more attention. It even has the holocaust and Nazi dictation as themes.