My understanding is yes and no. In the pre DX12 era drivers often contained full replacement shaders for games sometimes. Where the OEM would hand write a repla

My understanding is yes and no. In the pre DX12 era drivers often contained full replacement shaders for games sometimes. Where the OEM would hand write a replacement that worked better than what the game dev did, potentially on a GPU sku level. They would also potentially completely re-write how sections of the pipeline worked with shims for the same reasons. This was sustainable because shaders were relatively tiny (look at the limitations of DX9 shaders vs DX10+), and the pipeline relatively simple. However moving forwards to DX10+ and shader size explodes, as does pipeline complexity, and shader count. While they still did this for popular titles by special agreement, they largely switched to issuing guidance and providing tools to devs to optimize their games. But the issue persists. Writing shaders for Nvidia's warp system will potentially compromise performance on AMD, Intel etc. So OEMs still do some shims for games when performance is particularly egregious. But with DX12 and Vulkan in particular it's more about having presets for things like you'd find in NVidia control panel and a few game specific optimizations to critical paths, instead of just replacing how that game interacts with the driver completely.