You can say this as long as you want, Nvidia makes money hand-over-fist supporting CUDA alongside OpenCL and DirectX. It's all just business to them - they don't have to play the same game as Apple because they're just not quite so petty with the ecosystem politics.
Look at MacOS, for example. Plenty of legacy software never was supported in Metal, it's "implementation detail" never manifested. It wasn't even really used in AI either until Apple upstreamed their own MPS hacks into Pytorch and people got BERT et. al. working, and even that was a pint-sized party trick that you could do on a Raspberry Pi. Apple themselves aren't even using their own servers for serious inference either, because you can't. It's gotta be offloaded to a lower-latency platform.
It's not just that Metal as a platform has failed it's users, although it's certainly contributed to developers giving up on Mac hardware for serious compute. Apple's GPU design is stuck in iPhone mode and they refuse to change their approach with Apple Silicon desktop hardware. It was Apple's big bet on NPUs that hamstrung them, not an implementation detail, and if you don't believe me then wait and see. Xserve didn't tear down the 1U market, Asahi didn't upend Linux HPC, and Metal isn't going to upend AI compute any more than DirectX will. This is the same "Apple will get 'em next year" quote we always hear when they fuck up, and they never actually seem to swallow their pride and take notes.
