Fundamentally it is more efficient to process a batch of tokens from multiple users/requests than processing them from a single user's request on device.
Until Apple or AMD unifies their GPU architectures and implements complex streaming multiprocessors, Nvidia will remain in a class of their own. Apple used to lead the charge on the foremost CUDA alternative too, but then they abandoned it to focus on proprietary standards instead. It's pretty easy to argue that Apple shot themselves in the foot with every opportunity they had to compete on good faith. And make no mistake: Apple could have competed with Nvidia if they weren't so stubborn about Linux support and putting smartphone GPUs in laptops and desktops.
[0] https://apnews.com/article/apple-ai-news-hallucinations-ipho...