True, but as long as there are rules, somebody is going to find a loophole or a way to game the system. I'd personally be more concerned with Google improving their product or with society's increasing reliance on a single company's service and our unwillingness to consume information critically.

PBNs are garbagey, but trying to put them all down is unrealistic. And even if they could be stopped, it would only be a band aid fix, not addressing the real problems.