This is the long term result of Apple not wanting any further dependency on AMD/Nvidia, but at the same time not realizing that AI was going to hit and be very, very Nvidia centric.
But for most tasks which were known to exist 5+ years ago when these decisions were made, their on die gpu really is plenty fast and offers a larger memory area than most every gpu known to be coming at that time.
Apple has AI hardware acceleration in their devices.
Nvidia's advantages in AI come from industrial grade hardware that lives in datacenters, and Apple hasn't been competitive in datacenter hardware for decades.
But for most tasks which were known to exist 5+ years ago when these decisions were made, their on die gpu really is plenty fast and offers a larger memory area than most every gpu known to be coming at that time.