Comment by skrebbel

This is because Carmack doesn't really do OSS, he just does code dumps and tacks on a license ("a gift"). That's of course great and awesome and super nice, but he's not been painstakingly and thanklessly maintaining some key linux component for the last 20 years or something like that. It's an entirely different thing; he made a thing, sold it, and then when he couldn't sell more of it, gave it away. That's nice! But it's not what most people who are deep into open source mean by the term.