> Unless a subreddit is heavily moderated, I've yet to see one that's gained popularity outside of its core users that didn't turn into a meme/clickbait/karma-motivated cesspool.

Well that's a weird condition given that all the good subreddits I know owe this entirely to moderators. Why are you looking for lightly moderated content?

I'm very much in favor of heavy moderation. However, I realize that it's a difficult task when moderators aren't paid and users are joining exponentially.

There are also niche-topic subreddits, which don't face the overpopularity problem by definition.

But sure, the best subreddits tend to be heavily moderated and/or very niche. Is this really a problem?