While you might consider software that runs on the internet to be part of the internet itself, not being able to run some of the software doesn't mean you can't access the internet.

A little bit less pedantically though, while this is certainly a blow to internet freedom, and not a good thing, I think most of us would agree (at least in the long-term) that access to the web is more important to freedom that a collection of proprietary apps.

what critical stuff is not avaliable via web browser but is via app?

Banking, for one.

why would banking not be avaliable via www?

Many banks don't provide HTTP endpoints (except for business versions). My bank, Monzo, does not. My other bank TSB does provide a website, but it's awful.

Wait, you have to use a smartphone app to interact with your bank? There is no website with 95% of the functionality (or bonus functionality that the app doesn't have) available as a website for desktop users?

This is rather unusual, the credit union I use in the USA offers an iOS and Android app that is literally a webview of their mobile website, plus a dash of OCR for check handling. Using the PWA is nearly identical, it even works on a PinePhone with Maemo or any other operating system that can run a semi-modern browser.

Yup that's pretty much it. To Monzo's credit they seem to make a point to work without Google Play Services, but iOS users would be screwed in the event the App Store was blocked.