Of course it does. Sandboxing even exists on Android. The criticism here is that if you have some system that has root and can poke through sandboxes that you can access this data.

You either have full access or you don't.

That wasn't my point. It was that iPhones need not limit apps to the "App Store" in the name of protecting the system, since it can sandbox apps, wherever they come from.

If the non-app-store-installed apps are sandboxed then they cannot actually run everything that tinkerers want and the same criticism persists. The "we don't own our phones" crowd wants root.

That's a different complaint though. Just allowing sandboxed, sideloaded, apps would enable a whole host of new apps such as emulators, plus it would allow apps to provide their own monetization (e.g. Fortnite).

There’s a far larger number of iPhone users that either don’t know what root is, or don’t care. And your parent post is incorrect, Apple denies apps all the time.