Great comment, I've thought a lot about similar ideas. We're just getting started with sharing + discoverability and already working on a feature to surface popular modifications for a given page you are visiting.

The hardest part is doing it in a way that is privacy-first and not annoying. Done wrong, it's kind of like injecting unwanted popups, and no one wants that. Not to mention properly handling points 1-4.

We very likely won't get it perfect on the first try, but hopefully with a few iterations of user feedback we can tune into a useful system.