Please consider this an example proposal. There are a lot of potential pitfalls with comment moderation, so I don't want people to get too excited about this particular idea. It occurs to me that since we really want to hear your ideas, seeding the question was a mistake.
At 30k on graduated sites (and 10k on beta sites) grant users the following powers:
- Access to the comment flag queue
- Delete comments
- Purge comments (i.e., one click to remove all comments on a post)
- Move comments to chat
- Access to deleted comments on the post page via a menu option
- Undelete comments
- Access to comment edit history
- Edit comments
- Convert to comment
I'm suggesting these privileges because comments are one of the few things that elected and appointed diamond moderators can do something about that the rest of the community cannot. Other than flagging, there's no way for regular users to fix problems with the comments on a post. Having a powerful privilege to aspire to provides a better incentive than providing somewhat less-powerful privileges. Anecdotally, people most look forward to the 10k privileges which introduces the final piece of community moderation: post deletion.
I estimated enthusiasm following a privilege level by doing a longitudinal study of median time-to-next-action. Looking at the 868 Stack Overflow users with more than 20k whose accounts were created after 2010-10-05 (the date privilege notifications were first issued), we can see how quickly they posted and edited after gaining each new privilege:
||participate in meta
||remove new user restrictions
||talk in chat
||edit community wiki
||view close votes
||access review queues*
||edit questions and answers
||create tag synonyms
||cast close and reopen votes
||approve tag wiki edits
||access to moderator tools
* The access to First Post and Late Answer review queues is an outlier because it was introduced around August, 2013. It’s a good guess that most of these users got notified of their new privilege when they had far more than 500 reputation.
These are exceptional users, so they participate (as a group) far more than others. If we look at users with more than 5 reputation, the median first post after getting participate on meta is 215 hours. Compared to their later behavior, trusted users start slow. Notice that they also slow down again after hitting 10k or so. Critically, the slow down after 10k also occurs for 30k users (N=429), so it’s not just an artifact of the cutoff.
There’s circumstantial evidence that increasing the top privilege level increased participation at higher levels. More to the point, the relatively underpowered 15k and 20k levels appear to be less effective at motivating users than 10k powers. So introducing something really helpful, such as comment moderation, seems in order.
However, I think comment moderation is mostly a waste of time. I'd much rather let the system handle comments. Unfortunately, there are already so many comments that should have been edits (or even answers) instead that we can't blindly hide/delete old comments. Creating this privilege will mean committing to manual comment moderation for the foreseeable future. Comment moderation is tedious and unrewarding so I'd rather have our top users do something more productive with their time.
Therefore, while this is my best idea for a new privilege level, I'd really rather find something else. Please consider answering with your own idea and/or upvoting better answers.