All of this talk of ms drivers being behind comes from one article on edge that doesnt even name a source.
If you read that entire article which in my opinion is nothing but click fodder at the very end of the article they also claim that the ps4's graphic driver is also quite lacking. You never hear anyone even mention that part of the article though. All this from a company that has already picked which console they are backing (ps4) and posted it as a major headline a few months ago.
Edge also had an earlier article with Avalanche saying MS were behind back in May.