Keep in mind that HN also has a "deep thread" mechanism, which hides the reply button for a while on sufficiently deep comment threads to discourage rapid-fire posting without thought. (Slashdot used to have the same thing; if you posted comments too rapidly, you'd get a "whoa, slow down there".)

I'd also hope that more weight goes to "more commenters than upvotes" rather than "more comments than upvotes", though as vague heuristics neither seems too far off.