What led to the split? (Another noob question, I know.)
This can be answered many ways and in varying levels of depth but basically a large contingent of people didn't want to be known as a DT fan forum any longer and regardless of any polls that were made to gauge how the members felt, the administration changed it to a general music forum overnight basically.
So those who were there because they were DT fans who wanted a DT forum to post on, made their own.
I mean, there's a lot more to it, but all that amounts to is drama.