It not obvious to me that POB doesn't work at all, because we've never had an economic system since inception that made any sense.
POB requires honest voting, that is to say a decent correlation between one's subjective opinion of content and it's rewards and exposure. All we know for certain is that if this process is completely undermined and out competed by vote selling, circle jerking, self voting etc. then the platform isn't worth shit. Maybe it still wouldn't be worth shit anyway, but I'm optimistic that that's not the case. We've just never had it before so we simply don't know.
Thankfully the economics is no longer directly rewarding dishonest voting 4x more than honest voting. So it's worth fighting for a functional system, we may be slowly working towards it. Everyone needs to compete fairly on the basis of their content to attract votes. We can't accept vote buying/vote selling as the norm, because then we're back in the dark ages again. What I find especially bad is when vote sellers get people to dump steem for their shitcoin which is then used to buy votes. This not only undermines competitive honest voting, it puts downward pressure on Steem price at the same time and we should fight against this.