> This is, at least in part, a result of MINIX using a highly permissive license.
Not at all. MINIX was actually Intel's second choice, they tried first to fit Linux into their new x86 based ME. But the maintainers were uncooperative:
And this shows that the license really isn't that critical. Vendors don't like to maintain operating systems, so they have a vested interest in upstreaming their modifications. Why maintain something yourself if you can get someone else to do it?
BSD licensed projects see plenty of contributions, they're just not as popular as Linux because of historical reasons. I and most BSD fans blame the AT&T lawsuit for BSD losing popularity and Linux gaining popularity. That being said, BSD is still quite popular, though somewhat niche.
Companies not upstreaming code will happen regardless of the license. Plenty of companies maintain Linux change sets because they're not obligated to release them, but plenty more upstream their changes when not strictly necessary. It just depends on the value proposition of releasing improvements.
BSD licensed projects see plenty of contributions, they're just not as popular as Linux because of historical reasons. I and most BSD fans blame the AT&T lawsuit for BSD losing popularity and Linux gaining popularity. That being said, BSD is still quite popular, though somewhat niche.
Companies not upstreaming code will happen regardless of the license. Plenty of companies maintain Linux change sets because they're not obligated to release them, but plenty more upstream their changes when not strictly necessary. It just depends on the value proposition of releasing improvements.