I don't like the mob thing either but it's how large group dynamics on the internet work (by default). We try to mitigate it where we can but there's not a lot of knowledge about how to do that.
It's ridiculous that this impromptu feedback session is happening here in a sub comment of a trivia thread that many users will just overlook. Feedback and community engagement should be an ongoing, (semi-)formalized process, not an ad hoc, once in a blue moon type of thing that will have been buried under a deluge of garbage by tomorrow morning.
It's really weird how two of the most important platforms of the open source world (HN and GitHub) have no feedback process in the commonly accepted sense. Every niche Python package has an issue tracker nowadays where problems are collected, discussed, and often resolved, with the synergy of the community of users. But the grand systems underlying all of this are somehow exempt from needing anything like that, and "email the moderators" is good enough? I don't buy that, sorry.
There are many variations of this feedback system, but comments randomly interspersed in unrelated discussions, never to be found again, is not one of them. And neither is a private mailbox.
I'm also not sure that an internet forum like HN is a good fit for the issue tracker model—but that could just be rationalization on my part.
Don't you get tired of answering the same questions again and again, and rebutting the same arguments year after year? I can't imagine not being able to just write "Duplicate of #3845" and close the issue.
You know that what you're saying is "I can't imagine not being able to show the user a middle finger?", right? Because that's how it usually feels on the receiving end. You mentioned StackExchange upthread; the identifying meme of SO and SE family is "closed as non-constructive" and "closed as duplicate" - that is, how absurdly many good topics are killed or blocked this way for no discernible reason.
For Dan, I imagine the amount of work is the same. He could be clicking[0] to close ticket #12346 as duplicate, and making it clear to the entire HN userbase that user 'TeMPOraL just wasted his time by having the audacity to ask question without first searching[1] through prior #12345 issues. Or, he can just make a few keypresses to insert a canned paragraph into an e-mail[2] - resulting in me getting my answer/scolding directly into my inbox, but more importantly, in me feeling heard and respected as an individual contributor, as well as being reassured HN is moderated by someone who cares. Not to mention, I can always reply if I believe I'm being dismissed too early, without risking to create a stink.
Same amount of work, completely different outcomes.
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[0] - In some crappy modern issue tracker WebUI. Like the GitHub one you mentioned. Or Gitlab.
[1] - Via some crappy, eventually-consistent Elastic Search-backed search form.
[2] - Or, these days, he should be able to forward the e-mail to DanGPT, with an annotation like "doesn't work, gtfo, hash table in the sky", and DanGPT would then produce a few polite and informative paragraphs, based on the forwarded e-mail and maybe automatically pulled comment history. I wouldn't really mind to be on the receiving end, even if I learned this is how the reply was written. It's still much better than "Closed as duplicate" or "WONTFIX" or "LMGTFY".
So having a public issue tracker reduces the number of issues the maintainer has to respond to, because it enables (certain) people to answer their own questions by looking at what has been discussed previously.
There are very good reasons for why issue tracking is now the standard for 99% of open source projects. It's not about having fancy web UIs, it's about the process itself.