I could be wrong, but my understanding is that when
d20pfsrd.com added the storefront and became a profit making website they were no longer able to post anything non-OGL or Golarion-specific and had to make things... "generic"... for lack of a better term.
The
Archives of Nethys on the other hand is still able to post most anything due to no profit being made from the website.
I could be grossly missing the particulars, but that is my simple understanding of what's happening between the two sites.