OK I remember that one actually. I interpret that as, here's a blank piece of paper. There are endless possibilities to what can be drawn on this page until somebody draws something. As a blank sheet the scope is endless. But to actually draw something useful would limit what it could be. So leave it blank?

Since comments are already treated differently to posts you could just as easily say restricting us both to the same pool limits the scopes of steem. And I would say that it does since there is far less incentive to comment than there is to shitpost.