Comments like the GP have been affected by the recent change we made to make some downvotes more powerful (cf. sama's recent post on this). We did this to address HN's toxic comments problem, but it has a downside: some good comments get caught in the crossfire. It's not that they're getting more downvotes than before, it's that you see it more because they're getting counted more.

The HN community has long had an informal self-correcting mechanism for this case: when fair-minded users see a substantive and civil comment unfairly faded out, they upvote it back to par. We're encouraging everybody to do this consciously. The hope is that the overwhelming majority of good comments will come to rest in positive territory, while comments that deserve it stay negative. Exactly this happened with the GP.

In general, it's best to give such comments a corrective upvote yourself and trust your fellow users to do the same. "Why was this downvoted" posts mostly add noise—especially once the comment in question is back at par. (We're seeing a lot of this.) If it turns out that it's necessary to rally corrective upvotes—that is, if casual reader attention isn't enough—we'll figure out an unobtrusive way to achieve that. For now, though, let's wait and see if it is.