Carmack says... (k3nshi)

Carmack:

The scope of what we have to do in a modern game is too much now for one person to do everything. But any time you break past the point where one person can manage all aspects of it, there's this incredible cliff you fall off in terms of average effectiveness and productivity. As soon as you need to divide a project, everybody is less efficient than the one person originally doing it. Plus you have the parasitic management overhead on top of all of it."
Carmack refuses to take on the role of manager -- he'd rather program. "The sad part is, I could probably do, effectively, at least half or two-thirds" of the programming for a modern game single-handedly, he says.

Read the rest over at Wired.