If they didn't review every app, someone might sneak in a paid app without giving Apple and Google their 30% cut.

If you have no gatekeeping, then all of the bad actors come in and you end up with a tragedy of the commons.

Apple did this correctly, IMHO, when the App Store first came out by both:

- reviewing all apps

- having it take 30 days to get the feedback

The 30 days seemed draconian or bureaucratic but it forced builders to be 100% sure that there app was working and ready for consumption. It probably also acted as major friction for scammers etc who figured it wouldn't be worth it.

The iPhone 1 only allowed web bookmarks. They aren’t as capable as real apps in dozens of ways. The fact that lots of Apps are just glorified web site browsers doesn’t mean there aren’t plenty of apps that aren’t, and some that couldn’t be done with a web site at all.