That's true. Take the Redox project that's been moving along nicely. Or Haiku, Syllable, MenuetOS, etc. All of them had small teams with external vontributors that got plenty done in terms of a usable OS.

Whereas, a fast, standardized browser like Firefox takes a huge company to support it. The complexity is just huge. Plus, the standards and web experience are always moving along. Can't wait for more people to scratch an itch if you want to stay competitive.