The same would still be true of all the apps in the App Store. There would just be other stores. You wouldn't have to use them. Other people could.

The issue here is that many people want the hardware or the OS without the App Store. If you give it to them, "people who only use the Apple App Store" will be a smaller number of people and Apple will have less leverage.

That's the point of prohibiting anti-competitive practices. Apple does a lot of things with that leverage that are bad. Like prohibiting apps that compete with theirs (e.g. browser engines), and imposing political censorship in authoritarian countries, and extracting 30% from captive developers.

You presumably want Apple to have the leverage because then they can use it against e.g. Facebook. If everybody on iOS thinks like you then you win -- everybody only uses the App Store even though other stores are available and Apple still has all the same leverage.

But if most of the people disagree with you, right now you're holding them hostage. Forcing them to use only the App Store even though they don't want to, so that the world's largest corporation can have more leverage.