Yes, Windows has a stable driver API you can build upon.
Linux does not, because they want all drivers to be inlined (included in the kernel) and open source. nVidia does not want to release their trade secrets, so they don't want to open source their drivers.
Except that AMD doesn't have feature parity with Windows driver on open source version and has all the Nvidia driver headaches on closed source version.
They are not behind their windows driver on OpenGL. And neither for Vulkan, I think. AMDVLK scores a few wins here and there, but RADV is generally more stable, performant, and compatible. Plus being open-source, it is easily extended, like valve is doing with their AC0 experiment [1].
Last I heard, people were installing Linux to use the AMD OpenGL drivers to play emulators (it might have been Cemu, actually ran trough wine).
It doesn’t have “all” the headaches on the closed source version, afaik - it still implements the standard APIs and thus works with systems that were designed to work with every other driver from AMD to Mali, unlike the nVidia proprietary driver.
Definitely, it's his software and he can do whatever he wants, and I'm not criticising him, I'm criticising Linux for not offering a stable driver API. As far as I know they don't even want to allow shims like the one Android Treble introduced. It is not a technical decision, it's a political one.
Seriously though, one of the pleasurable things about using macOS is that you don't have to worry about hardware compatibility. Because there is none, outside the small list of parts officially supported by Apple itself. There are some NVidia cards on that list, yes.
Linux does not, because they want all drivers to be inlined (included in the kernel) and open source. nVidia does not want to release their trade secrets, so they don't want to open source their drivers.
(No idea about macOS)