Only if it's free to post, right? If no one has skin in the game, then you'll get spammers. Consider a simple system where people pay 10 gold to post and 1 gold to vote. At the end of the month, the pot of gold is paid out to the top posts and the voters who made the best bets.

I am not a game theorist/economist, but perhaps there is a set of rules such that every actor in the system is rewarded for their proper usage of the system, otherwise they get penalized, but this is only possible if it requires stake to be in the system, which is impossible in "free and always will be".

It needs to be expensive to go against the community, which is why actions should cost a nominal amount of money. If this is the case, dividends or incentives could be paid to users for participating in a productive protocol.

(Edit: Of course, there will always be the people who have tons of money and can manipulate the system, but how is this different than people with tons of money who buy account farms and drive impressions, e.g. fake news, ads, etc.?)

Isn't Youtube actually trying something like this, where community members can get paid to be moderators, essentially?