I've been reading this site for a while now. I notice in most discussions that a large percentage of commenters have their text greyed out. From watching, it appears that this happens either when a bunch of people downvote them or when a privileged user does something to their post.
Which ever the cause I think this is a policy that is harmful to deep and meaningful discussion. There's no doubt that this sort of "public muting" will have the affect of reinforcing group think. Does it seem healthy to do this to opposing views? Shouldn't we all desire to have our beliefs challenged by alternate viewpoints once in a while?
I see grey text in every thread, about every subject, for what appears to be any reason at all. Every day I see polite, reasoned opinions, about things that are far from "settled matters", even about such things as esoteric as Javascript code architecture, muted for saying something against the grain.
This is not a positive thing.
I ask that you please cease this absurd practice. If a post's content is inappropriate or detracts from a discussion, please remove it, but please stop this group think enforcing policy.
A YC Moderator responded to a similar post alleging that it was necessary to maintain civility. If someone reading this is a Moderator, I dare you to do a test. You have the resources. Select several hundred suppressed comments at random and tabulate wether there is abuse in the post, or if not then tabulate it as disagreement. This is the sort of thing you are paid to do, so do it!
As you say it's actually being used to suppress divergence of opinion. Every time it's done to me, it takes longer than before for me to resume commenting on HN. Eventually I will stop.
What can be done? Sufficient loss of reputation points for a down vote etc. would probably be enough to discourage frivolous actions.