I was looking back through this thread and trying to determine where this conversation became specifically about selling Poser/DS only content and noticed that I'd missed this comment before:

Razor42 posted at 10:50AM Sat, 11 February 2017 - #4296776

In fact I do not think I could name a single vendor in this market sector that sells exclusively through their own site? So I'm not sure where the proof of concept is here?

Xurge3D. (Unless he/they sell at one of the big sites under an entirely different name and style, which I doubt).

Target View 3D. Used to sell at rdna. Also sells content for Maya and other platforms.

And there are a number of other content artists that sell through their own sites - some of which also provide content for Maya, Max and other platforms, on the same site, as well as sell through all the major Poser/DS brokers.