On top of what Marcan posted: keep in mind that back when Nouveau development started Linux open source graphics stack was young and had no mature drivers to lo

On top of what Marcan posted: keep in mind that back when Nouveau development started Linux open source graphics stack was young and had no mature drivers to look at. Only in last 4 years graphics stack feature and performance parity thanks to Intel, AMD and Valve. Today LLVM is well-developed for GPU drivers and there is tons of other ready-to-use code for OpenGL and Vulkan implementation. E.g RADV was initially created by two developers only and now it is better than AMD official Vulkan implementation. On top of this modern GPUs are now less complex to develop drivers because they'e decoupled from display controllers and hardware no longer have fixed pipelines.