> Having a smallish team makes it possible (although not easy) to have a team that are all high performers. And that team can easily outperform one 2x-5x as large if not more, because there is a large communication overhead to scaling to more people.

^ This. As the project gets larger you can't find enough "star programmers" in a timely manner and have to fall back to mediocracy. Read "The Mythical Man-Month" and the associated Brooks' Law for context.