I think this is a really interesting question as I loved Slashdot's moderation, but I wonder if it results in less engaging (ie less toxic) behavior. Good question ... fartcannon!
I think that at the time when Slashdot slid from mainstream as a discussion platform, the top complaint was that the site's moderators were deciding the posts that got to the front page. Only after Digg and Reddit captured a lot of their original audience, did Slashdot introduce the "firehose" concept, which showed all submissions, before being vetted by the mod team.
Until then the process was that someone would submit a post, someone from the mod team would review (and, maybe edit it) and only then it got to the front page. This, in my opinion, allowed for better quality, despite some of the biases the mod team showed. The community was adamant that it should be in charge of what makes it to the front-page and in this regard Digg and reddit were doing it better, so Slashdot became less and less relevant.
