That's a completely different scenario and those IT departments already have their own mechanisms of enforcing lockdowns, they wouldn't want others to impose lockdowns on them (the administrators) too. For devs, such an Apple imposed lockdown on MacOS would destroy the Macbook's popularity, since it would regress and turn into a glorified ipad.
A locked-down MacOS would be awful but at least you’d still have Linux (thanks Asahi).
With an iPhone you are stuck with whatever new decision from Apple with no opt-out. That’s abnormal.
See, I’d be ok to say that Apple can do whatever they want with iOS the day they give me the keys to the boot loader. Until then, they’ll have to assume their role of gatekeeper.
I have no issues with walled gardens as long as you’ve got the key to leave. Here the key to leave is called "throw your $1000 phone to buy another".