[kudu]

> Ad blocker extensions are a major security risk

This is only true in the sense that an all-purpose browser is "a major security risk". That is to say, it's not true in any coherent sense.

Yes, the ad blocker needs to be trustworthy, and there are a variety of approaches for furthering that goal.

> Adblocker extensions need full access to all network traffic and all it takes is a single person's account or machine to be compromised to get access to millions of browsers.

Again, you could say the same about the browser itself. Even if it were infeasible for extension developers to implement more security safeguards, that would be a flaw in the Chrome Web Store, not in the concept of web extensions.