Huh? Most useful APIs will allow access to some data/data source.

The whole point of computing is to work with interesting data and process it somehow.

It's up to the user whether he allows the app to both access interesting data and the network, or only allows the apps that can work with the data locally.

Also, this API would be much less sensitive than allowing apps to access contacts list, or whatever, for which the API already exists.

The application in question had access to all of your communications going to the internet from your device.

The whole purpose of computing is not to have access to all of your private information and to analyze it and sell it to third parties. They even admitted that their business model was fashioned after Onava’s that did just that and was bought by Facebook.

I was talking about Apple providing api to get information about screen time of other apps, so that these kinds of monitoring apps don't need such hacks.

This is also why Facebook bought Onava. Even without access via a VPN, that would have been enough information for Facebook to know that people were spending a lot of time on WhatsApp and to know that it was becoming popular. Would you be okay with that?