In theory. In practice, strong moderators become more important the larger the community gets. And reddit is a very, very large community.
>The whole driving premise of Reddit is the upvote, and that's an incredibly powerful concept.
It's powerful, but not always in a good way.
I think one of the better examples is looking at the difference between /r/gaming (light moderation) and /r/games (heavier moderation). While I am sometimes entertained by the content on /r/gaming, in general, it's a terrible subreddit that does a good job of soaking up most of the crap discussions surrounding gaming (5 threads a day of "Has anyone else ever played Zelda?"). Whereas /r/games actually has content worth reading a vast majority of the time and it's not just a filtered versions of /r/all for threads that have "game" in the title.