Comment by talldayo

It is entirely Apple's fault that they rejected OpenCL to replace it with a proprietary library. If this was an implementation or specification problem, Apple had every opportunity to shape the project in their own image. They cannot possibly argue that this was done for any other reason than greed, considering they themselves laid the framework for such a project. Without Apple's cooperation, Open Source GPGPU libraries can not reasonably target every client. Apple knows they wield this power, and considering their history it's both illogical and willfully ignorant to assume they're not doing this as part of a broader trend of monopolistic abuse.

Having shut out Nvidia as part of a petty feud, Apple realized they could force any inferior or nonfree CUDA alternative onto their developers no matter how unfinished, slow or bad it is. They turned away from the righteous and immediately obvious path to complicate things for developers that wanted to ship cross-platform apps instead of Mac-only ones.