I doubt that code will ever get to the point where it couldn't be undermined in some way. People always deviate to some optimal meta-game rather than follow developers intentions / societal constraints (proof-of-brain). Even when I was playing with developing better filtering systems, a subset of users managed ways of abusing it. Systems that rely so hard on mechanics to make people behave tend to become fragile to individuals trying to find weaknesses in those mechanics. There's a reason why hackers exist.

This would suggest figuring a means of cooperation at higher social levels. While social networks can enforce some rules, the more decentralized they are, the harder it is for these networks to enforce particular rules.