If push notifications are so bad why does every mobile app spam me with them?
All of these things "users don't want" are right there for use in App Store apps. They're only held back from the browser because they want you to give them 30%. In some cases they literally added features to Safari but restricted them for use in advertisements only (WebGL for one example, IIRC) because the features aren't the problem, the problem is developers accessing customers without paying 30%.
Many push notifications are spam that developers want to send and users don’t actually care about. But more than that, the fact that you actually downloaded an app is much higher proof that you want to get notifications than just going to a site and clicking yes on a dialog. Dialogs basically mean nothing because users will just click yes without thinking about it.
All of these things "users don't want" are right there for use in App Store apps. They're only held back from the browser because they want you to give them 30%. In some cases they literally added features to Safari but restricted them for use in advertisements only (WebGL for one example, IIRC) because the features aren't the problem, the problem is developers accessing customers without paying 30%.