That is great, you can avoid using app stores you don't trust. Why prevent other users from using stores they trust? Apple isn't the only company that can run an online store. There are countless online web stores selling all kinds of things, and people trust them with their money. Apple is artificially preventing competition in iOS stores here because they can abuse their dominant position.

The biggest issue is that in a native app you can fake the entire display. There is no way to know if it is a store you trust. It could look just like your paypal login down to the last pixel and it instead be bad actors collecting your information.