Earlier quoted context omitted.
This is not the right attitude. People should be allowed to participate, and they can downvote whenever they see fit.
That's not participation, that's violating community protocols. Downvote is not used to show that you disagree but that the reply is low effort, inflammatory etc.
Whereas upvotes and downvotes control the sort order without silencing anyone, reflecting (albeit noisily) the overall community sentiment. Voting based on agreement is a perfectly valid way to use HN, and it seems to be what the majority is doing. (At least judging from the votes on my own comments, where I can see the count.)