That isn’t consistent with the difference in dependency on advertising that occurs from app to app. It could be, however, that the device-level prompt could set

That isn’t consistent with the difference in dependency on advertising that occurs from app to app. It could be, however, that the device-level prompt could set the default for future app-level prompts. (That sounds annoying in retrospect, but maybe the right way.) Another consideration is your point that preventing ads will harm advertisers’ income. In some cases, hurting income is an acceptable loss, but in others where the service is sustained by advertising, less so. Perhaps another compromise could be to allow apps that do not accept the tracking prompt to only access basic functionality, with an explanation that the tracking supports their premium service. That’s a very different world for Facebook and others.