Are you seriously arguing that the web does a better job of respecting user privacy than desktop and mobile operating systems?
This is well understood by the adtech industry and is why so many websites push apps in the first place.
Do you think an iPhone with the tracking blocker engaged is still a richer source of data than the web app on an iPhone? Facebook claims that Apple's privacy protections cost them $10 billion of revenue the first year.
When i close the webpage, that page is gone. It's not running in the background silently collecting data. With a properly configured browser (a few extensions, no third party cookies, or even separate containers), it doesn't have much data to gather in the first place.