The worst thing that happened to Unix was the MBAs at AT&T and then Novell wanting to extract the maximum possible revenue from it. Whilst large vendors licensed the code, e.g. IBM, HP, Sun MicroSystems, sundry workstation vendors and Microsoft (Xenix!) it was off limits to universities. So Xinu, Minix and subsequently Linux emerged. BTW Plan 9 and Inferno were also subjected to the heavy handed monetization efforts.

Had AT&T taken an enlightened approach, the brilliant folks at universities would have worked to improve it (granted Berkley did contribute, but they too were sued) instead they wasted time reinventing the wheel.