DAZ is only a reseller for Poser, like they resell XFrog plants. That's all. E-On sells a Poser/Vue/Mover bundle and a Vue/Lightwave bundle - does anyone thinks E-on will buy Poser or Lightwave?

Regarding P6 support - a lot of the new products have P5/P6 mats included now, some products are even P5/P6 only because it's dynamic clothing or it uses the material nodes to create special effects. It's up to the indivdual PAs to include support for all versions of Poser and DS or only for the version they are working with. DAZ tells no one to not support certain versions of Poser.

Every organisation rests upon a mountain of secrets ~ Julian Assange