Until the competition publishes an app called iMessage with a surveillance backdoor (unless you’re proposing phones perform DPI?) and the helpful, inevitable “merge app stores together” app that would be necessary in that world subsequently prioritizes the bad one, or users assume the bad one is the right one, or, or, or. There’s a million threat vectors for their model that don’t dissolve down to a technical mechanism.
Much of the security gained from having a single App Store is not technical in nature but rather reflects (conscious) security policy. This should be apparent. Fundamentally server people chafe at this but look at how much security work (and failure) goes into routinely running hostile code not written by you, particularly on the hosting side. Cloud providers have armies dedicated to the exact same security problems that app stores must solve and it is very often not good enough. That’s fine when nerds are involved but more people than nerds use phones.
Much of the security gained from having a single App Store is not technical in nature but rather reflects (conscious) security policy. This should be apparent. Fundamentally server people chafe at this but look at how much security work (and failure) goes into routinely running hostile code not written by you, particularly on the hosting side. Cloud providers have armies dedicated to the exact same security problems that app stores must solve and it is very often not good enough. That’s fine when nerds are involved but more people than nerds use phones.