alt Hacker NewsSee the first message of TFA. The author complains that amdgpu has way too many linuxisms that make it impractical to port it to non-Linux ( unless you are already emulating Linux). On the other hand, the nv kernel driver is portable, up to the point that it is easier to port that to Haiku and then change the entire Mesa to use it than it is to port amdgpu (which wouldn't need Mesa changes).
Of course a Linux driver is going to make use of Linuxims. That’s literally the point of a Linux device driver.
Given how performance-sensitive device like a graphics card is, you’d naturally want as few abstractions between your OS and your hardware as possible.