So the privacy angle is pure bullshit.
They are removing, among other things, the ability to dynamically cancel requests, and replacing it with a declarative API. That limits how well an adblocker can function.
The good ones will still want onBeforeRequest() for heuristics and dom access for click-to-block.
The whole privacy excuse from Google is intentional hand waving. Decent ad blockers will still need permissions for scary sounding things.