But that's not the point of a reference implementation,
I agree that's not the point of a reference implementation. The MIT license is a good license for a reference implementation, as is the BSD license. The question was whether it is a good license to advance free software or not. That was the argument. The goals of a reference implementation are not the creation of a free software ecosystem.
You don't know that they would have even bothered with X at all,
I don't know. But it is likely. X was the GUI for Unix. Unix was a cheap operating system that allowed hardware vendors to create workstations and then servers without investing a ton in software. Much the same role as Android (another Unix flavor) plays today. If they didn't use X and went with another GUI they would have had to invent it and support it on an ongoing basis. I can see SGI and maybe Sun. But would DEC for example have wanted that for their GUI? IBM? HP?
Then Linux fails that metric in almost all cases too.
No it doesn't. Linux as used in almost all cases is open source freely available software. The big distributions are mostly free or at the very least have free versions. Linux as an operating system mainly sells support or hardware.
Show me that claim in the context of a "BSD license failure" then.
Just keep clicking parent from this very post. You'll get to this: http://slashdot.org/comments.p...
The 3 examples to prove that the open version wouldn't be replaced where:
OpenSSH, Apache and X11. X11 of course is the example that the GPL have used for 30 years since it was such a disaster. OpenSSH has had problems. Apache has been more of a mixed bag, it mainly has remained free with a broad community of support. But a lot of the advanced capacity is proprietary.