Well, sure, and you can try to and some even succeed in jailbreaking their iOS devices. That doesn't mean that Apple should be anything but hostile to such attempts.
We've reached the first point in recent history where we're really seeing products with actively anti-user features at scale. Coffe machines that only take proprietary coffe pods, printers that have DRM on ink cartriges, and more. These are all on a much smaller scale than a computing device that we use for a significant portion of our lives, both for management and entertainment.
Another comparison would be a car that can only drive to restaurants that agreed to give the car company 30% per customer that arrives in one of their cars, and there have to be fences around it to make sure you're not walking to the restaurant next door by foot.
I'm not sure I agree with "I should be able to sell anything with any anti-features I want" anymore to a certain extent, since it does affect such a large part of our lives, as general computing machines.
Arrangements that subsidize a large purchase (printer, paper towel dispenser, coffee maker, razor, smartphone, tractor, etc.) by locking the purchaser into an exclusivity agreement for consumables from the same company (ink, paper towels, coffee pods, razor blades, smartphone apps, tractor maintenance, etc.) are as old as these have been feasible. This innovation tremendously benefits both parties. I'm not sure why you'd dispense with it really.
