Many of Apple’s “security” policies are fundamentally editorial rather than technical restrictions. How do you propose that such editorial policies be enforced? For example: an app which targets children and asks them to supply personal information.
Similarly, Apple’s new, much-lauded anti-tracking policy does have a technical component to it, but it would be easy enough for motivated developers to get around it. All that stops them is app review, or more precisely, the threat of app review.
In both cases, I assert that such editorial control cannot survive store diversification. Right now the App Store policies are able to nudge developers towards pro-consumer behaviours. Any substantive amount of store competition flips the script and means stores will compete to appease developers, rather than apply principles in the long term interest of consumers. The nanosecond after Apple is forced to change their product, big names like Google and Facebook will be the first to set up their own shops, specifically to escape Apple’s pro-consumer editorial policies.