That's AMDs fault, not Nvidia's.

AMD is incompetent on the ecosystem layer, but Nvidia has certainly been acting malicious.

I've laid out my thesis at length in past comments, which I don't care to repeat, but the gist is: During the ~2010-2014 period (the time where the ecosystem gap really widened), Nvidia purposfully didn't implement OpenCL 2.0 while pushing CUDA, which made cross-platform solutions uncompetitive.