What is UNIX, Anyway?
Lieutenant writes "Technology professionals have loosely used the term "UNIX" since the first person had to explain the difference between the Berkeley and AT&T flavors, so it's not surprising to find as many UNIX standards as there are versions of the operating system. Peter Seebach wades through the wellspring of UNIX standards and sorts them out for you, concluding that the rumors of the death of UNIX are (as usual) greatly exaggerated."
You are referring to Systems Software Research is Irrelevant (aka "utah2000"), but I think you miss the point, just because Unix being "good enough" killed all progress doesn't mean that it was a good thing, quite the contrary.
And BTW, Plan 9 has a Unix compatible subsystem called APE(A Posix Environment), but it is rarely used, because Unix is 30 years rotten shit, and all that was worthwhile keeping from Unix has been in Plan 9 from the start, all that others have added to Unix in the last 30 years have been hacks by people that never understood Unix and its philosophy.
The true Unix spirit is still alive and well, in Plan 9, but not in any of the bastard sons of Unix or its numerous clones.
"When in doubt, use brute force." Ken Thompson