I also think something important here is AMD's strategy with APU has been small to large. Something that really stood out to me over the last few years is that NVidia was capturing the AI market with big and powerful GPU while AMD's efforts were all going into APU research at the low end. My belief is that they were preparing for a mobile-heavy future where small, capable all-purpose chips would have a big edge.

They might even be right. One of the potential advantages of the APU approach is if they GPU can be absorbed into the CPU with shared memory, a lot of the memory management of CUDA would be obsoleted and it becomes not that interesting any more. AMD are competent, they just have sucky crash-prone GPU drivers.