If Melinda wants to use the Facebook app, but the Facebook app is only available on the Meta store, then Melina is forced to use the Meta store. This is not giving users choice. This is replacing one corp-backed store by multiple corp-backed stores. The user loses.
The only way how this would be a choice is if the same app, with the same basic functionality was available on all stores. Then the user would really have the choice which store to use. Or if there were alternative apps on different stores. Good luck with that given the current monopoly markets.