GPL is also part of the problem. Linux will simply never support HDMI 2.1 properly because the license precludes it. It will never support OSS like ZFS properly because the license precludes it.
It is a restrictive/closed copyleft ecosystem by design, and that’s actually completely unsuitable for a world where you must have some kinds of software (including open/libre software) and some parties simply will not license that way.
(And I know people will object to the term but it undeniably is more restrictive and closed than BSD/MIT/CDDL-style licenses - intentionally, openly, and by design. The point is that you are supposed to license your software GPL too - and when that is not possible, your freedom is denied. Intentionally, by design. But it is a closed ecosystem - you are either in it, or not, and there are large swaths of code (even open/libre code) that is excluded by design. That is a closed model, just as much as, say, CUDA. You play by their rules or you play in a different sandbox. And open CUDA code exists too, etc - that doesn’t mean anything to the overall ecosystem if licensing precludes people from using it.)
The minimum standard for even reaching usability would be to guarantee a BSD-style stable ABI such that kernel upstreaming is not required in the way that it currently is, and that’s a nonstarter with the current kernel leadership team. Actually they have in many cases gone out of their way to explicitly break compatibility to push others to relicense, even when they know that it’s not going to happen and their users will suffer.
When you get to the point of rejecting interop with other libre code due to license, and actively take steps to break other libre code to prevent interop - you certainly are not fully libre in the typical sense anymore. There’s a degree of fairly open hostility to other libre code at this point, in fact.
Again, it’s not 1992 anymore, Linux could absolutely maintain a stable ABI through major releases. Not only do they not want to do that, they are actively, willfully, maliciously breaking other libre code (GKH has done this repeatedly). Which gives sort of a different color to the former: kernel upstreaming is one of the most potent weapons at this point, for pushing more stuff into their closed ecosystem. It’s not exactly embrace-extend-extinguish, but certainly of a similar tone and kind - join or die.