I see it as a giant argument chamber. You can't say the "sky is blue" without someone asking you for sources or ackchually-ing you because an eclipse darkens the sky, etc. People deliberately take the most disingenuous reading of commentary and respond to it to make the poster look as stupid or insecure as possible. I can't see how that is an echo chamber. (and I see the irony in opposing your statement here, while making the claim that most comments are disagreements). I will concede, however, that certain topics (teslas, apple, among others) there is a hive mind that will downvote viciously if you hit a nerve.