>I can't help but think that if the Linux kernel were under a CC-NC-BY-SA-type license, as you suggest, that it would be practically unheard of today.
I don't suggest that the Linux kernel be distributed under non-commercial terms, and I agree with you that such a project wouldn't have done well.
>BTW, please mind the distinction between open-source software and Free Software. You don't have to like the FSF, but the distinction they recognize is important.
Right, so there are 3 levels of "purity" here. For the record, I didn't run afoul of any of them; I intentionally distinguished my suggestion as "source available", not "open-source".
There is "Free Software", which is software meeting Stallman's "Four Freedoms".
There is "Open Source", typically referred to as the improper noun "open-source", which activists insist refers solely to license approved by the OSI (Open Source Initiative). Because these include permissive licenses, the FSF considers them potentially non-free, and makes the point that Open Source isn't good enough; it must be Free Software.
Then there is "source available", insisted upon by the OSI people, to indicate that while you can download and modify the source, it is not distributed under copyright terms they like. This would be source distributed only for non-commercial use, for example. Jef Raskin's Archy project (apparently now dead) [0] was distributed under CC BY-NC-SA and made this distinction.
[0] https://en.wikipedia.org/wiki/Archy