Unfortunately Sun won the System-V vs BSD "Unix wars", and then uni(x)laterally capitulated to AT&T.

The Day SunOS Died

    "Bye, bye, SunOS 4.1.3!
    ATT System V has replaced BSD.
    You can cling to the standards of the industry
    But only if you pay the right fee -- 
    Only if you pay the right fee . . ."

http://www.poppyfields.net/filks/00070.html

For context, the guy who wrote "The Worst Job in the World" email was Michael Tiemann, one of "open source's great explainers." ;) Now he's pranking IBM executives by installing RedHat Enterprise Linux on their mainframes.

https://en.wikipedia.org/wiki/Michael_Tiemann