Even the NVIDIA drivers on Linux are superior to macOS' drivers. The problem with the NVIDIA drivers is that they don't play well with the rest of the ecosystem, but they do work. The only area where Linux is behind in graphics is on mobile, where the GPU vendors are perpetually unable to write working drivers.
I'm a professional graphics developer and I prefer the tooling on Linux to that of macOS.
Like most software developers, graphics developers develop where the users are. That's why they predominantly use Windows. Some use macOS, primarily to develop iOS apps, which is, again, where the most valuable users are, particularly in North America.
Linux desktop market share, or lack thereof, has nothing to do with graphics tooling.
Sure it does, why bother with a market that not only lacks customers, it makes it a major hurdle to develop for?
While anyone on Apple and Windows platforms can enjoy Metal Frameworks, DirectTK, Unreal, Unity, CryEngine, PIX, Poser3D, Photoshop, Houdini, Cinema 4D, AfterEffects,...
On Linux, I guess having the freedom to use half baked copies of them, or hunting for libraries that should come out of the box with any graphics stack like 3D math, mesh handling and loading materials, is more important.
I'm a professional graphics developer and I prefer the tooling on Linux to that of macOS.