I don't mean to marginalize the gnu project, but there were already free -nixes out there. Starting over from scratch isn't much of an accomplishment other than the license...
>and created the culture and licenses that made it possible
The GPL has ultimately done more harm than good for open source. The only time proprietary software vendors are forced to release anything is when they accidentally mess up because they didn't understand what they were getting into. This happens rarely and when businesses get burnt, they're more apprehensive to do anything with opensource in the future. I know because I still see this happening today.
When people aren't scared of the codebase, they can start using it. If they can modify it without worrying about legal repercussions, they're not afraid to modify it. Sure they don't have to give back, but if you force them to they're not even going to make the modifications in the first place.
If someone wants to build something closed source, they're going to build something closed source even if it means re-inventing the wheel to avoid the GPL. I'd rather have the wheel be a BSD wheel, so even if product X will never be opensource, at least it will be built with good wheels. I'm a realist that knows closed software isn't going anywhere and at the end of the day I'd like all software to be as good as it can be.