No one would force you to use third party app stores.
The way it is now is very straightforward. If you want an app, you know where to get it. You know who’s vetted it. You know who’s handling your payment info. You (now) know what information about you is being gathered and disseminated.
Can you imagine how terrible a world where every App thinks it needs its own store would be?
Having a uniform way to handle payments is a great feature, but it would happen naturally if payment terms were competitive with industry norms instead of extractive prices that require a lock on distribution.