The problem is that of a chicken and egg situation.  Vendors don't want to make new stuff that is only usable in the newest version since it will cut out some possible sales.  Therefore, trying to find stuff to use in the newest version is hard to locate so people stick to the old version which makes vendors say see everyone uses the 12-year version, so there is no need to create for the new version.  Me, I make everything in the latest version and if it happens to work in a prior version great, if not oh well.  Of course, I do it for the fun of it and not to make a living.  The nice thing about the last couple of versions is that you don't need a massive number of nodes in the material room to make something look good.  That along with the fact that you can now render without any lights and get good results in a short amount of time gives me a bit more time to work on fixing OLD materials to make them work in Poser 13.  

Poser 5, 6, 7, 8, Poser Pro 9 (2012), 10 (2014), 11, 12, 13