Yes autofocus is brilliant for snapshots but technical skill still hasn't been entirely replaced by the technology yet. I only used the D3X as an example of viewfinder blackout btw, not autofocus. I mainly used it with manual focus and old lenses, like the 200mm f4 macro.Not going to get into a discussion about AF systems, No AF system is 100% but used correctly it's really good. (Still no mind reader)
Deer in bushes, single point 3D AF tracking. The old D3X have a really old AF system made in 2007, better than my crappy D90 but a lot worse than the new AF systems from Nikon/Sony/Fuji/Pentax
Problem is that no AF, as far as I know, is point and shoot, but need practice and training to get it right.
My Olympus OM-D E1 has pretty well instant autofocus with the modern lenses, certainly faster than I ever was manually focusing, but yes, I still have to use my knowledge to force the issue to get what I want in some situations autofocus can't deal with.
Autofocus has got better and, particularly, faster since my first autofocus camera (Canon EOS 620) but still haven't tried anything perfect for portraits with fast lenses or wildlife.
Good for landscapes and kids though.