i think it's because of how connected bronydom is. there are a gazillion places to see starwars stuff, but almost all brony communities draw on EQD, FiMFiction, and poni/derpibooru. so when you look for good fiction you can find the best in the entire fandom, not just what one community produces.
or at least that's been my experience. i fell out of love with fanfiction a while ago, but mlp brought me back with it's sheer volume of quality writers.
but lets not make this more pony than it already has to be and get back to the fanfiction.