In the teams where one person does more than all others combined, why is that described as "a successful team" rather than "a successful person who succeeds despite a bunch of hangers-on"?
I think that's looking at it the wrong way - you have one person who's talented and/or hard-working; contributing to the majority of the project and the others are the supporters - they're function may be primarily to allow the core contributor to do what he does best and while they take care of the more mundane tasks, provide their knowledge / experience and so forth when needed.
A little bit of encouragement and support goes a long way.
IME it's usually the other way around about who's doing the mundane tasks. Occasional contributors are most motivated by getting in their one pet feature; it's the project leader who takes on the dull task of cultivating an environment where other people can bolt on that feature successfully.
A little bit of encouragement and support goes a long way.