I think that HN appears to do the things Dash suggests, but actually fails at a number of levels. Since dang took over he's been much better than previous moderation about responding specifically to people, but it's still done infrequently and haphazardly. What's actually necessary and implied by Dash is the continuous feedback loop between moderation and community, which explicitly excludes hellbanning, deading threads, and other forms of heavy-handed moderation without concomitant explanation of reasoning. This is, as you note, a very large problem and likely impossible to solve with a low level of staffing and any belief in the ability of automation to guide a community of individuals.

But there are worse things than being an echo chamber, and preventing those worse outcomes takes priority.

I would disagree on this, but I see where you're coming from. HN serves a lot of purposes to a lot of people.