Same for your memory bandwidth argument. I'm not claming the M3 Ultra is faster than Nvidia nor that memory size is "everything", but if you have a model that is too big to fit in VRAM or unified memory, then memory bandwidth is worthless because the model will become so slow it becomes unusable. The M3 Ultra is a compelling option compared to spending the same amount on crazy Nvidia server GPUs and it is better *in some ways*.
Also your premise of using marketshare as a mark of superiority is ridiculous. By that logic, Windows is the best OS on the planet. Nvidia has a monopoly which didn't even start with AI, it started with PC gaming. It was dumb then and it's still dumb now in the AI age.
Bottom line, Apple can do whatever they want. They are not technically incapable. If they wanted to compete with Nvidia in the server AI space, they can. Apple's priorities are often not fully understood, and sometimes they are just downright screwy. I don't agree with all their decisions... or maybe even most. But Nvidia sucks as a company and their products are way overpriced and overrrated. And again, Apple's inablity to make a smart Siri or do whatever else with AI models has nothing with their ability to make hardware. Honestly I strongly believe Apple's inability to turn Siri into a smart LLM comes down to one thing: LLMs are extremely chaotic and unpredictable, and Apple hates that. They are control freaks and they prefer a dumb Siri to an unpredictable one. Their rigidness is holding them back, as it often does.
If you ever watch Alex Ziskind's Youtube channel, he has tested LLMs on many different hardware and Apple Silicon often beats Nvidia in many use cases, especially when price is a factor. It is a viable competitor, whether you want to admit it or not.