My question is, if reddit were on that list, would the moderation system be able to prevent it turning into Digg? I don't think it could, although maybe the subreddit system could. Places like /r/politics/ are fairly useless for intelligent debate already. Such link sharing sites don't have the same "my friends are there" grounding force that Facebook has, it's just the "vibe" and community so running away to a new site is easily mounted.