First, each Blake version was written by a totally different authors AFAICT so while each version is faster, making a faster construction was a totally differen

First, each Blake version was written by a totally different authors AFAICT so while each version is faster, making a faster construction was a totally different team. I don't see why you're putting so much confidence that the original SHA-2 team could come up with a faster hash function. FWIW, SHA-3 is slower than SHA-2 although of course SHA-3 is a totally different construction from SHA-2 by design.