On the bright side the situation is at least better on Windows - D3D11 and D3D9 both have well-specified behavior and full software rasterizers that can be used to render a reference version of a given frame and then debug it at a pixel level. Wish I had something like that for OpenGL... console game developers have had toys like this for ages.

It's 2020 and I still sometimes swap my renderer from OpenGL to D3D9 when I need to debug a graphics issue because the D3D9 graphics debugging tools are that much better than cutting-edge GL debuggers. (I'd use the D3D11 debugging tools but my 11 backend doesn't work right)