It would be good to provide a link. I've been through the last 8 days of pg's comments which you can browse here and haven't seen anything to that effect:
Discussions will end up quite boring if people use votes to agree or disagree rather than expressing their point of view in a reply. I tend to think of votes on HN similar to the options for moderation on Slashdot: vote up for insight, vote down for off-topic or flamebait.
I have had this bookmarked for more than a year, as this issue comes up over and over and over again. Sometimes downvotes to express disagreement with the stated position in a comment is the most concise way, the way most friendly to other readers of HN, to indicate that the comment didn't add value to the community.
Of course, pg is experimenting right now to see if different software settings make upvotes, downvotes, flags, and so forth have better or worse effects on the community as a whole and on particular threads.
https://hackernews.hn/threads?id=pg
Discussions will end up quite boring if people use votes to agree or disagree rather than expressing their point of view in a reply. I tend to think of votes on HN similar to the options for moderation on Slashdot: vote up for insight, vote down for off-topic or flamebait.