The "convoluted" way is/was the default in the absence of a monopolist app store. Before centralised app stores, users downloaded or bought boxed software ad-hoc and installed it on their computers from installation archives, just like you can install apps from APK files on Android. If you banned Google from preloading their app store, isn't that what we would revert to?

The goal is not to prevent a Google monopoly. The goal is to have competition to prevent Google abusing its monopoly to lock down users.

There is Samsung Galaxy store.There is Xiaomi store.There was Amazon app store which failed to gain traction as it was not pre-installed but had decent number of apps. This is even before we get to open stores like F-droid.

Now their viability is a question in the long term, if Google has complete discretion over what is allowed.

On my Nokia (featurephone) you don't need to install apps, you just run them.