The iPhone released without an App Store. Their original plan was very clearly to limit it to web apps. Apple, including Steve Jobs, spent a lot of time and energy explaining why web apps were the best option.

And then Apple realized, largely through apps developed for jailbroken phones which led to a lot of people jailbreaking their phones, that for iOS to really succeed they needed apps.

Windows Phone 7 is another example of this. It was a superior OS to iOS by most measures. It died almost entirely because of the lack of major apps.

If major app providers (Google, Spotify, Netflix, etc) had never made their apps available on iOS and had made them available on Android instead iOS would probably be looking like Windows Phone 7 right now.