> I'm confused how the "inner browser" meaningfully helps you accomplish this.

Right not it is not hard to write an adblocker, just block network requests and DOM elements (regardless of whom hosts of proxies them).

A browser in a browser would make blocking dom as hard as attaching a debugger and manipulating a price that has been hardened.

Network requests may still be able to be blocked, but it is going to make ad blocking harder.