Whatever their apparent intention might have been ~15 years ago, it would be hard to argue that Apple puts a lot of resources into trying to protect its fiefdom. I don't think it would be all that different to suggest they (Apple) wouldn't try to control how people pay for apps by preventing app developers to offer a web-based payment option, on the basis of their past relationship with HTML5. A huge component in their success with iPhones has been control over the entire supply chain.
That said, it is a somewhat conspiratorial take that is probably better explained by laziness, bad choices, and control over proprietary UX patterns (that suck), than generalized competition, but it's not much of a reach. They also compute localStorage limits differently and have always diverged for stupid reasons