Another account of mine was hellbanned for triggering some automated response based on voting patterns - which were very suspicious, but had a legitimate reason (specifically I downvoted comments that were of topic, which was most if not all the comments in that thread).
It makes sense to me for someone to down vote the most top-level comment that led to an off-topic thread. But then further down voting comments that are replies within that thread makes little sense, and could be mistaken by some as vindictive down voting (which is likely why the automatic ban you describe exists).
Further, if there are enough replies in a given thread such that your down votes on all of them were enough to lead to a ban, it strongly suggests that the thread really was on-topic, that it generated valuable interest and discussion, and that actually it's just a controversial thread (one you may not like perhaps), but clearly not off topic.
I do see this a lot on HN. When a thread is controversial in a way that HN group-think disapproves of, then "off topic" is used as an inappropriate excuse to down vote it, try to derail any discussion about it, etc.
For example, I think effectively all of the stuff from the subreddit TheRedPill is utter nonsense, and it's often very controversial and I dislike it when some of it appears here at HN.
But it's rarely actually off topic when it's brought up, and it generates actual community interest (usually from people who rightfully point out how problematic and baseless it is).
I'd rather that controversial topics and tangents, even when they are things I don't like, are permitted when they clearly generate community engagement, than to basically have some implicit HN blacklist of disallowed topics that are facetiously treated as off-topic as a way to simply exclude unapproved opinions.
It would be nice if HN had some way to say, "this whole sub-thread together tanks the SNR". Sometimes a thread will go wildly off topic, but there are so many replies off the topic that more interesting on-topic points can't be raised above the noise. Sometimes I wonder if this could be a deliberate astroturfing strategy.
One recent example was a useless conversation about whether the US was a democracy or a republic, with 10 different people saying the same thing. Those 10 comments with replies fill several scrolling pages, so the real topic of conversation is buried.
On the other hand, you could argue that if a comment generates substantive replies (as opposed to just replies that say "this is off topic") then it's actually pretty strong evidence that the community feels the comment is on topic.
In fact, I think it would be a good thing if it was made impossible for moderators to detach comments that receive enough up-votes, or have child comments (especially comments that disagree) with many up-votes.
In those cases, it's clear that community members get value from the comment, which should infinitely override bespoke opinions of whether it's "on topic enough" to remain -- those subjective opinions ought to count for way less than simply observing whether there are up votes or replies.
It only takes about ten redundant comments (wild guess number) to derail a thread for thousands of would-be participants. This doesn't indicate community value; at best it indicates accidental nerd sniping, and at worst could be a coordinated attack on what would otherwise be a productive discussion, from which more people could derive far greater value.
But the comments are drawn from the distribution of Hacker News readers. You can't presume that just because you see a thread of ten comments as an off-topic distraction that so must the other thousands of readers, especially if there are healthy replies and up votes.
Your comment that it "derail[s] a thread" makes the implicit assumption that the comments are actually off-topic. If they are on-topic, but you happen to have the opinion that they aren't (even thought they are) then it's not derailing anything, it's just a healthy reflection of the comment-generating process that is "the pool of all HN readers." I think of it like the John Lennon quote: "Time you enjoy wasting is not wasted."
I don't have a magic answer for how to accurately detect off-topic diversions in a way that satisfied most people most of the time. All I'm saying is that upon seeing a healthy back and forth, it should give me a lot of pause that if I merely think it's off topic, I am probably wrong, and it's just an opinion that should not be indulged by moderator activity.
Interesting points. I'll just add that I don't think that enjoyment is the best metric for evaluating a thread, but maximal enjoyment and/or maximal usefulness. Especially if what I'm calling off topic prevents the community from addressing a threat to its values. I could be wrong, but it seems that the HN team want HN to be more than just a fun place to hang out for hackers.
There was another example of derailment recently, with a dozen comments arguing over what a "middleman" is when the original comment was really about how best to support indie makers.
Anyway, thanks for the interesting discussion, and I hope I haven't made this thread less useful for someone else in the process.
