Agreed.

It's quite easy for an open source project to just waddle around and start blindly accepting things random developers contribute with no real decision or filtering process (cough PHP). They may verify the code's not buggy or that it at least does something that could be of use to someone, but they generally don't care if it fits in with the overall design and goals of the project.

Having someone who has the complete vision in his head, who's also extremely technical and knows what changes are good and bad, is absolutely invaluable.

Linux is not just code. It's a brand, a community, whatever. As people on HN should very well know, success is mostly about execution and luck - lot of people have very good ideas. The reason behind Linux being so successful is only partly attributable to it's technical merit (well, from the technical standpoint it didn't have anything too exciting when it started to have traction). It had to have all luck, good moments, industrial/social situation what eventually made it successful.

I don't think luck plays that big a part. But regardless, As you said, execution is very integral to the success of the project and since Linus, has executed the project so well over the years, it does say something about the execution style(it works and people still support him as well as the way he leads :).