Apple makes sure it's not practical.

You still can't have a "share to" target that is a web app on iOS. And the data your can store in local storage on safari is a joke.

Of course, forget about background tasks and integrated notifications.

In fact, even on Android you miss features with web apps, like widgets for quick actions, mapping actions to buttons and so on.

And no matter how good you cache things, the mobile browser will unload the app, and you will always get this friction when you load the web app on the new render you don't have on regular apps.

Service workers solve the cache issue; web apps can run permanently offline after initial load. You may be a bit out of date on the state of the web.