I really think that the HN guidelines need updating, so that we're directed to consider those comments the same way we do accusations of astroturfing:
> Please don't post insinuations about astroturfing, shilling, brigading, foreign agents, and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data.
It "degrades discussion" in exactly the same fashion.
Except "usually mistaken" doesn't apply here, since it's often true.
The position of "Degrades discussion" in that sentence implies that the accuracy of the claim has no bearing on that particular impact.