Because they have to reinvent the wheel every year. And why do they have to reinvent the wheel every year? Why else how do they sell the same damn phone every year? And from that damn phone comes everything else: 3 or 4 generations of the gyroscope from the Watch S4 to S8/Ultra, why then if the useful sensors (glucose in the blood) do not put them? To enter the “in case you overhang with the car the watch saves you”?
Apple has obvious limitations in engineering and programming, but for decades now, not since yesterday. They focus on the product that produces the most receipts and the rest goes to the swamp, they dislodged it precisely to make it compatible with that phone toilet to which every 4 years they change something just to change it: TouchID on several iPads and Macs, FaceID on iPhone X; Notch on Mac, DI on iPhone; OLED screens on Watch and iPhone, LCD on iPad and Mac;On Apple Watch they changed 3 times, 3 times, the function of the button !! But how do you break your HIGs every 3 years?!
Is it possible that as soon as users learn how to use a feature they have to change it to show that they are doing something when in reality they are doing nothing (just damage) other than trying to sell the same product every year?!
They are saved just for Apple Silicon, for now, until systemic bugs come out like for Intel.
So much so that the only hope left is that the toy they showed will become the core business of the company and suddenly cancel everything else, so they can focus on making 1 product, but maybe do it decently. And no, that the competition is worse is not a justification.