Step 1: Buy new car
Step 2: Replace engine with something other than OEM.
Step 3: Complain when car's ECU does not run engine.
Step 1: Buy a new car
Step 2: Replace engine with something other than OEM
Step 2.33: Car runs fine
Step 2.66: Manufacturer comes to your house and 'fixes' your ECU while you're asleep
Step 3: Complain when car's ECU does not run engine
I’m asking hypothetically of course...
There are anti-trust laws against 'tying agreements', and forcing consumers to only buy components from Apple (due to tie-in) would be violating those laws.
That said, those laws don't say anything about having to interoperate with an inferior part.
So assuming Apple isn't willfully violating anti-trust laws, we can be fairly sure the change was intended to improve some aspect of the touch controller.
Note: There are exceptions if the tying serves a purpose other than maintaining a monopoly (such as the security pairing between the TouchID sensor and FaceID camera).
1. But new car
2. Replace broken windshield with something other than OEM
3. Complain when car refuses to start because its computer detected a non OEM windshield.
It was not fine. Rain sensing didn't work again for the rest of the time I owned the car.
Sounds like the early 1990's.
It would be perfectly reasonable to not force updates and allow users to continue with the current version forever if that keeps them running. But it's not reasonable to just break people's functional devices with an unavoidable update.
It's not a perfect analogy, but the rules on radio interference with devices spring to mind: you need to cope with some interference and you need to not emit it. This results in a more stable ecosystem, even though you could sensibly argue that if one side is stuck to absolutely, the need for the other wouldn't exist.
But even if it wasn't, it's not entirely outrageous to predicate continued software support on some terms. The only problem then would be not making those terms clear up-front.