I wouldn't assume the Zbrush users all stay in their forum, or that the DS users all stay in the DS forum. The mixture you are looking for is already here around us, or at least those who want to mix know where to come. The poor Poser users users don't have the luxury of a nice quiet forum at Renderosity, where they can choose to stay and avoid the rest.

For better or worse the Poser forum is the hub of Renderosity, or at least that is the way it seems to me after 15 years or so. Maybe it would have been better way back then to have called this the general forum, and to have had a subforum that was Poser specific, but that's not what we got.  

Willow, and Jack, and all the others that have come and gone, some sadly passed on. There is a lot of history here. It's kind of sad to see it getting torn up so a few folks can watch a fight or two.