What's clearly fundamental about the human/chimpanzee advantage, the thing that made us go FOOM and take over the world, is that we can, extremely efficiently, share knowledge. This is not as good as fusing all our brains into a giant brain, but it's much much better than just having a brain.

This analysis possibly suggests that "taking over the world's computing resources" is the most likely FOOM, because it is similar to the past FOOM, but that is weak evidence.