Not entirely true. Some of the very large subreddits such as /games and /askscience have actually retained very high quality. They just require very strict rul

Not entirely true. Some of the very large subreddits such as /games and /askscience have actually retained very high quality. They just require very strict rules and heavy moderation. Just compare the frontpage of http://reddit.com/r/gaming http://reddit.com/r/gaming with http://reddit.com/r/games http://reddit.com/r/games — granted one is about twice as big as the other in terms of active users, but /gaming has been full of low-quality submissions since before it became a default subreddit. It just comes down to having proper rules and enforcing them. Now, reddit and 4chan are very different in the regard of perceived quality. If you heavily moderate a subreddit the low-quality submissions will for the most part only be viewed by those that browse the queue of new submissions. This isn't really true with 4chan since the low-quality submissions that are buried will still be viewed by everyone (although this kind of depends on if you've configured the order of submissions). As an interesting aside, you can actually significantly impact what submissions get buried in a subreddit with very few votes since there's not a lot of people that browse the new-queue.