Yes, people on the internet will be negative. No, that doesn't mean you should respond to them.
Here's an example of a negative comment that (rightly) hasn't been downvoted: https://news.ycombinator.com/item?id=12509856
Here's an example of a negative comment that (rightly) has been downvoted: https://news.ycombinator.com/item?id=12508752
If sama is talking about negativity in general, then it would be a very sad thing to complain about people being negative. Because negativity is important, especially in discussions, especially for the reasons you touched upon. But I assume he knows better than to complain about people disagreeing.
I think he's just complaining about the number of people this topic has attracted that have come here simply to vent. And I agree, it's kind of a pain, but within a couple hours they get sorted out of the discussion. It's great that it's possible to say what they say on HN. And I just don't think it's worth complaining about, especially as someone involved in the production of the linked story. That's just feeding the trolls.