Spawning a Universe: how MLP Fanfiction created Sub-genres.

Many people have seen that there are many alternate Universes in MLP Fanfiction. These Universes are made by many writers and have many fans. These Sub-genres have grown over the decade that MLP: FiM has been around.

Universes, like The Lunaverse, Assassinverse, Hasbroverse, Fallout: Equestria, The Conversion Bureau, Fall of Equestria, Mykan's My Brave Pony among others, have their own fans and Detractors. These groups have made the genre into one of the biggest in all Fanfiction.

It is such that MLP fanfics have done more then any genre of fanfics, having their own universes and storylines that will last generations, even after those original writers have past on, newer fanfic writers will carry on.

any thoughts?