The problem with this argument is the existence of Android. The app ecosystem on Android is not appreciably better than iOS. Opening iOS to third party app store will likely just increase copyright infringement, leading to fewer paid apps.
It shows that there is some convenience from a "single" app store, such that people won't flood away and lead to a race to the bottom in quality. But it also shows that you can maintain that experience while allowing users to install whatever they want.
So Apple is claiming that allowing people to install whatever they want, or having multiple App Stores will lead to crumbling of the convenient and secure ecosystem that they have created. However Android has shown that this is not the case.
Anyway, the argument was that the Apple app store was stifling app development. In your reply you yourself say the apps on the Google store are “Maybe not quite as high” quality.
Which doesn't matter, because the person who is going to test your patch does, or the person who will write their own and submit it. Which makes the app better, for everybody.
> Anyway, the argument was that the Apple app store was stifling app development. In your reply you yourself say the apps on the Google store are “Maybe not quite as high” quality.
There is a difference between the quality of an app and the quality of a store. If Google Play contains all the same apps as Apple's app store, but they're higher quality because people hack on them more, it could still have a lower average quality if the store itself is less selective and there are also a bunch of lower quality apps. Which doesn't really matter because nobody is making you install those ones. Especially when you're not using the store for discovery to begin with, which they're increasingly useless at.
Also the "maybe not as high" comment was about security because you can make an argument that the human review is better. However there doesn't seem to be overwhelming evidence on either side comparing human review to mostly automated.