Throughout the history of computing, a ton of software has been licensed under a service/subscription model. There's nothing special about the web in this respect.

Throughout the history of the iPhone, iOS apps have been replacing activities that were done on webpages.

You make a very important point. There was a time when the community pushed back against the idea of a web that was subscription based, similar to the cable company model. It seems to be more palatable if we replace web pages with apps in this scenario. On the other hand... if a subscription model will dial back the reliance on advertisement income, and by extension the privacy invasion that comes along with the advertisement model, maybe it will be a net positive. If we continue to have excessive privacy invasions to support ad revenue and have to pay a subscription on top of that, then it will be extremely unfortunate. EDIT: a word