uBlock Origin via declarative blocks is almost as powerful as the original. While I would trust gorhill with almost unfettered control over my browser, I don't trust EVERY extension owner (no do I trust uBlock Origin in perpetuity).
A funny argument to make because the thing that would make such a measure ridiculous as you rightly point out, is exactly what already makes the Manifest changes ridiculous in the first instance. They were making a rhetorical point and you elaborated on their point for them as if doing so expressed a disagreement.