I suppose the question is why anyone would support CUDA only, instead of something like OpenCL. NVIDIA have been promoting CUDA quite aggressively for some time, but the bottom line is that even today, several years after these technologies became widely available, most mainstream applications for graphics, video, CAD etc. still don't use that power on either AMD or NVIDIA graphics cards. If CUDA really has meaningful technical advantages over OpenCL, why aren't these applications using it?