100% agree that human confirmation bias is VERY strong and impacts HN. This is partially the reason why I'm so concerned with (human) moderators having the ability to impact visibility of stories/comments[1].

Also, definitely agree that HN would be worse off without downvotes. I just think the system badly needs improvement. Below is a previous related comment of mine:

I think "downvoting for disagreement" generally works on discussion related to non-sensitive topics, but starts to break down once discussion enters the political realm. It turns into a numbers game. Since the dev community tends to lean to the left, the "downvote" numbers are skewed in that direction. It leads to non-left users getting frustrated and possibly no longer visiting the site (including myself), creating an echo chamber and eroding the overall quality of HN.

Why not set a max of 3 downvotes a day? Or subtract 5 karma points IF you don't include a reply with your downvote? There's gotta be a way to improve this.

[1] - https://news.ycombinator.com/item?id=23223555#23225685