Quote - So...the amended answer is Vendors can do it, it's their choice to produce Daz and Poser or Poser via Dson...think I've got it now;)

Much depends on what type of content they are creating and what figure they are creating it for. Currently there are three ways to rig a figure for Poser and two ways for DS. There is Poser Weight Mapping (Only works in Poser), TriAx (TM) Weightmapping (Works in DS, Carrara and, with the DSON Importer for Poser, Poser) and Traditional Poser rigging (Works in DS, Poser and Carrara). Figures with one style of rigging only work with clothing with the same style of rigging, though clothing rigging can be, with various levels of success, converted. 

So if a PA is going to create clothing for Victoria 6 then it must be created using TriAx (TM) rigging and saved in the DSON format. If a PA is going to create clothing for Victoria 4 then it must be created using Traditional Poser Rigging and saved in that format. If a PA is going to create clothing for Roxie then it must be created using Poser Weight Mapped Rigging and saved in that format.