Some software systems are too large for one person, however talented, to write. There's a reason not every line in the Linux kernel is written by Mr Torvalds.
But that's maybe not the best example; wasn't it originally just him? I think GNU+Linux might better demonstrate what you're trying to say.
It was originally, but I don't think it's controversial to say it wouldn't be in its current state as a 1-man project.
I believe Linus has said that lately, he doesn't write code so much as review and discuss patches.