This is more about the fact that when they take it it's worse for the project than a proprietary fork. When BSD/MIT/(other permissively licensed code) is used, modified, and re-licensed to GPL, the permissive project can't take those improvements without also re-licensing. The CDDL indeed saved illumos from being cannibalized and disappearing as a community. Had its features been easily ported to Linux without a licencing problem, the project would probably not have survived, simply due to the fact that there would have been few reasons to stick with it. It's not just about what code is out there, and you should know that.

>Actually, because CDDL is somewhat-but-not-really copyleft, many BSDs essentially have copyleft requirements if you enable ZFS or DTrace. Which is funny, given how much they go on about "freedom to make proprietary software" (something I'm against).

Only in regard to changes to DTrace and ZFS. Still totally fine to build proprietary versions of BSDs that include those pieces.

I won't go so far as the grandparent post here, but I'm one of those developers that couldn't give half a care about "user freedom". It's nice to have source as a developer, but my motivation has never been "freedom", insofar as using and understanding the software, so I understand where he's coming from in his complaints about the GPL. As a developer, it's more constraining than the permissive licenses out there. To some, that's a good thing.