[squeaky-clean]

I don't think they were saying to use blockchain to do this. It's just an example that shows that if you offer financial incentives in exchange for data people will exploit it and gameify it. The reason blockchain clearance rates are so slow is because of all the effort to prevent this. You could remove PoW from bitcoin and the network would be significantly faster. It would also be dominated by people exploiting it.

It's the same thing with ad networks, most of the effort goes into verifying that an ad click was legitimate and not a bot. Or that classic story of when the British government tried to eliminate Cobras in India by paying a bounty for every dead cobra, which just led to people breeding more cobras.