I don't agree. First, the people complaining about downvotes often really did write a comment worth being downvoted (I didn't look at your history). Second, HN is still very valuable if the top comments are all good - it's much less necessary that all good comments are on the top. And despite what people say, the key source of groupthink on HN is not the voting system (rather, the homogeneity of the user base.)