I want the staking mechanism to incentivise truth. Binary votes don't provide such a system. Binary votes (aka polls) can be useful to gauge opinions, but are insufficient to aggregate knowledge, and can easily be manipulated. Take for instance the stock market. If all a trader could do was make a binary decision of "Is this company good?" and they only get one vote, that doesn't generate any useful information. But instead ask them how much they're willing to pay for a share, then now we have high quality data about the value of a company, and that is hard to manipulate.