Just like in HN and 90% of forums on the Internet? The only difference is that Reddit threads tend to be so huge that less popular comments get buried easily.

Just like in HN and 90% of forums on the Internet? The only difference is that Reddit threads tend to be so huge that less popular comments get buried easily. I believe the issue has more to do with the subreddit structure and user moderation, which make really easy to create one-sided echo chambers.