Just imagine www didn't exist and Apple already had ios and apps. If someone came up with the idea of www and an app called web browser , would apple accept it in the app store? They would only accept it if they build it themselves. At some point is there a risk that Apple may also start to ban the web browser, despite that it's under strict control on IOS?
Apple/Google/Platform Owner will always do what's right for them, not the customer, and not the developer, for example banning Amazon from selling books in their kindle app, not allowing competing browsers (they recognise the power of the web as a platform), not allowing competing sales mechanisms (where they don't get a cut), and here not allowing developers to update their apps except through the store mechanism. I have some sympathy with Apple here, and see why they're doing it (they have to control what software is installed for security reasons as well as platform protection), but this is all about control over what you install on your own device. Sometimes their actions will be in the best interests of customers, even if not the best interests of developers, but most of the time their actions are simply aimed at preserving their control of the platform and control of the money flowing through it.
The web is the one exception to this rule which works across all platforms and devices (because it is so dumb and simple), and has survived attempts to corral it to a walled-in commercial offering remarkably well.