The community will act differently if they know others can see their behavior. Then again this may have negative effects.
I think that in general I'd be more thoughtful when voting comments up or down if I knew others could see.
I've probably voted thousands of times on various comments and articles on HN. Am I really going to care if someone sees that I voted this way or that way on some comment or other? I don't think so. I doubt many other people will either.