I notice this because these comments are valid and useful, and clearly show some interest and effort on the part of the commenter. They're not rants or trolls, but contribute to the conversation. (Random example: https://news.ycombinator.com/item?id=9423442)
Considering the recent post by Sam Altman about avoiding negativity on HN [1], I'm curious to understand what shift happened in the community. Has there been a memo that I missed about keeping things fiercely on-topic? Have more people been given downvote power and we're seeing the random result?
[1] http://blog.ycombinator.com/new-hacker-news-guideline
Edit: I see this post is getting more comments than upvotes, which will lead to it being flagged as "controversial" [2] and penalized :(
[2] see the always awesome Ken Shirriff's analysis: http://www.righto.com/2013/11/how-hacker-news-ranking-really-works.html