StackOverflow is HEAVILY moderated. And still has lots of garbage. I have questions constantly taken down for being too vague, offtopic, not the right stackexchange, or not technical enough. I've even responded to takdowns with links to questions with hundreds of points that were almost the same, and ... nope. At least mark it redundant.
Slashdot also had a great moderation system. Way ahead of its time.
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Edit: I was going to respond to [1], but I'm rate limited. Below is my comment:
> Anonymity really hurts profits.
That's what killed YikYak and continues to beleaguer anonymous message board monetization (well, maybe it's the content).
Reddit at least has an interest graph going for it. If they can figure out how to boost subreddit discovery and encourage users pick the things they'll spend money on, then they'll be golden.
