The very nature of the site, with posts, comments, and karma, encourages hivemind groupthink, and the design attracts primarily nerds and dorks as dedicated users. These people, many of whom are addicted to their computer screens, are usually moderately knowledgeable about most things (but not highly knowledgeable about anything) and, as long as they hold a popular viewpoint, they never have to defend anything against criticism. Since they were likely picked on as kids and maybe haven't had the best social interactions as adults, they feel the need to be tough on the internet. What you get is a bunch of self-righteous, ignorant, pompous, overly self-conscious individuals who will say whatever they think will get them the most upvotes, believe if it gets upvoted it must be true, and then look down on anyone who disagrees with the upvoted statement.