Physically can they? Sure. But there’s costs associated with that too. They’re clearly not hugely concerned with developer relations right now, but an ever changing “public” api certainly can annoy and drive off your developers in a way that a private and non existent api won’t. Likewise there’s an argument to be made that a constantly changing public API is also anti-competitive. If every iOS release winds up with breaking changes that force developers to update their devices and kill off devices that aren’t being updated anymore is that really any better than a private API? We already see a lot of anger over Apple dropping 32 bit libraries or how quickly they drop developer support for older OS versions and “force” developers to keep making updates to stay current on their public APIs.