seems you stumbled on the secret of keeping a good online community: don't let a person's contacts exceed the network's dunbar number[1].
non-default subreddits can still be quite good, but many/most/all of the default subreddits are wastelands ravaged by a silent majority of up- and down-voters while the huddled masses of commenters cling together for safety. of course, there's the same phenomenon within the commenters community, where insightful comments are buried amongst puns and prejudice and adolescent jokes that get upvoted much quicker.