Minix is BSD licensed and is present in Intel CPUs[0]. So I think it would be a toss-up as to whether BSD or GPL-licenses OSes are more widely used overall. To be clear, I'm making no comment on whether Intel using Minix is a good thing for their customers, but it's likely that the BSD license was what Intel wanted and caused it to become the most widely used OS few people know about.

[0] https://www.zdnet.com/article/minix-intels-hidden-in-chip-op...

Indeed, and where are Intel's contributions?

I know that was not your main point at all, but fascinating to see that MSVC is the only compiler to be fully 100% standards compliant (with only GCC being really really close).

My bad, your sarcasm translated badly in text ;-)