Why not apply some commonsense to onboarding? Accounts on HN start their lives shadowbanned, once you've gained some karma you can downvote comments and some point after that the ability to vouch for dead posts. I don't have any data on to what degree it works, but it would make the lives of those seeking instant "gratification" somewhat harder. Alternatively you could apply rate limits. Maybe new users could create a small number of posts on their first day and it gradually increases over time before the training wheels are kicked off entirely. Obviously neither option eliminates the need for moderators, but in theory you should be able to get by with less of them.