The Poser dev team had a webinar when P12 came out. I will try to explain it the way they did: In the old days when computers had limited speed and memory Poser would cut up the mesh into sections so it only had to deal with that one section you were working on (hand, finger joint, neck, etc) this made Poser more responsive for figure bending and animation. It also causes a lot of problems for figure modelers when a mesh is imported, worked on then exported back to their modeler. It f***s up the mesh verts and symmetry. There have been a few figures for sale over the years that have had mesh issues because of this. Now that everybody has super fast computers with gobs of memory there is no good reason to cut the mesh up into smaller parts. Once we get unimesh for Poser things like developing and importing new figures will be easier, also making clothing for these figures will be easier. Rigging and weightmapping should be easier. And when this goes live the dev team will be able to address things like animation, dynamics and color space.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740