You are right many good BTT forum members teleported their accounts. They were active in the beginning but slowly lost their motivation, my personal feeling is that I tend to get confused with the boards here.
I think the reality is much simpler. They teleported here for an extra income, but either didn't get a spot in any campaign or decided that payment rates were too low to bother with posting.
Personally, I find the novelty of the new forum quite refreshing, there are a lot of new things to explore, whereas after spending too long on one forum, things can get a bit stale.