In almost all cases, phone apps talk to that same central server as the web browser, just with a different (much worse) client that you have less control over.
If it were the case that phone apps weren't networked and could only sync through another channel like icloud/syncthing, then you'd be onto something.
But right now most apps are "web browser but worse".
Native apps might need networking, Web apps require networking, they might simulate offline to various degrees depending on local storage, which they don't have any control over, and is shared.
What you want is a better (and easier to use) sandbox for native apps, so that users can feel as comfortable installing an app as visiting a web page as long as the app doesn't have any more permissions than the web page would have, and then you don't need central gatekeepers approving them.
Just because the US has consolidated many ISP's doesn't mean the rest of the world has. Also, even in the US, that figure is just under 2k. Globally, it is >16k.
Also Web apps are basically the 21st century version of timesharing like in the good old days, where we had one server for everyone.
Even better for censorship purposes.