[Thrymr]

Unix itself was a commercial system, licensed by AT&T to various other companies, that nearly fragmented itself to death before being resurrected by the free/open variants (*BSD, GNU, and Linux). See https://en.wikipedia.org/wiki/Unix_wars

[api]

Everything was commercial back then. My point is that mature free implementations of Unix (BSD, Linux) came before free implementations of any superior systems and so they won.