I took these to be the same thing.

Ah, I think I misread the "to" as "for," but the second paragraph makes clear that my initial impression wasn't the intended one.

The question I have is whether intelligence foomed because it's useful for everything, or primarily because it's useful for social skills ("competition for dominance").

So, the more selection pressure, the better--so I think the fact that intelligence is useful for everything can only help. But is social skills enough to cause a foom by itself? It seems possible.