No, they're on Windows because it was the only viable gaming desktop environment during the 90's and 00's. Apple was all but dead and hardware was limited, Linux was in its infancy, Unix vendors didn't care about normal desktop users, etc...
In the early days of 3D gaming, there were studios that used OpenGL over DirectX on Windows. ID Software were the best known example of choosing OpenGL over DirectX.
Of course excellent OpenGL products exist (ID software is the worst example because they were... geniuses), but from the developer point of view, DirectX was the full package.
Forgive me for being an idiot but i was under the impression dx12 was closer to vulkan architecturally which makes it easier to port to Linux display drivers (and thus why it has)
1) OpenGL is a (now legacy spec) and DirectX is an API on Windows. OpenGL spec is implemented by your GPU driver.
2) DirectX is a collection of multimedia APIs on Windows. OpenGL is just graphics. Direct3D is one of those APIs.
3) Thirdly OpenGL and Direct3D (before version 12) are pretty much the same in they can do. The code is pretty similar IIRC (though it been some time since I've done Direct3D programming).
4) Devs use DirectX because there is a full set of APIs for the target platform. Linux and Mac aren't typically targeted when making a game. Mac and Linux sales have been a very small percentage historically.
Has there been a game where vulkan performance has been better then dx12? Whenever they are side by side vulkan always performs worse in my experience.
If games run faster on linux with DX12 translated to Vulkan than they do on identical hardware running on Windows 11 then I can't imagine a particularly big performance difference.
In the early days of 3D gaming, there were studios that used OpenGL over DirectX on Windows. ID Software were the best known example of choosing OpenGL over DirectX.