To be clear I don’t think this is an acceptable practice, but the concept wouldn’t be completely unfamiliar because Nintendo did this with the NES and their lockout chip/seal of quality system
It's a bit disingenuous to use customer base and the number of people who develop for the platform as a excuse to bring legal action against the company. Customers know what they were getting when they bought the phones and companies knew the rules when they chose to develop for the platform.
Consider Apple's very own Mac - another general-purpose computing device like the iPhone, only in a different form-factor.
Surely Mac developers must be tripping over themselves to throw 30% of their total revenue at Apple, as reward for their laser focus on privacy and security and for developing a nanny-platform that makes their users feel warm and fuzzy inside?
Surely Mac users must not be allowed to do business with literally any entity in the world without involving Apple as the gatekeeper?
Oh wait.
Everybody uses a phone, for everything now.