I think there should be many data servers with different rules. Some will blindly accept and serve any comments. Some will have mods and a buffer of comments waiting for review. Some will review only those comments that are flagged by their scripts. All these data servers should form a well connected network and exchange with comments. What's the incentive to exchange with comments? If a greedy data server refuses to give comments, others will block it. And users will be able to have multiple data sources, if (when) one big data server tries to use its monopoly power.