That's the exception that proves the rule. /r/askscience and /r/askhistorians have heavy handed moderation to keep quality much higher than the rest of Reddit.

I don't know how one can disagree with the fact that most of Reddit is quick engagement posts (images, memes, even if they don't fit the subreddit) and witty one liners voted to the top. There's good stuff, sure, the point is that it's hidden behind a ton of crap.