Why do downvote brigades even EXIST on this website? I feel like this upvote downvote garbage is an echo chamber in the making. Just sort comments by replies or randomly, or not at all. Or just have a "garbage post" flag and call it a day. Anything is better than this pseudo-democracy thing that Reddit has shown to be useless for real discussion time and again.

Agreed (and upvoted). I think HN has a generally high quality of discussions (except on certain political or fanboyism-related topics where only one side of the debate is tolerated). But, the best discussions on sites I frequent are on blogs that simply sort comments by time and thread, and where the host encourages open and intelligent discussion. Scott Alexander's (https://slatestarcodex.com) is a good example.

The flipside is that "report" buttons can become surrogate downvote buttons, and the lopsided volume of reports leads to inconsistent enforcement of rules, so commenters unpopular with the crowd or mods are more and more likely to be banned, while discussion devolves to groupthink, cliquishness and sycophancy towards the locally-powerful. IME BBSes are the most prone to fall victim to this; the communities are small enough that you can't be "anonymous," and with threads that can continue and be bumped to the top indefinitely, there's no mechanism besides moderator intervention to stop a flame war. Blogs and HN/Reddit-style aggregators do better because old threads are quickly buried.