What can you learn from that?

Admittedly, little to nothing, and I pretty much agree with your post. For nodes that have only a few responses, you might have a rough, and arguably inaccurate idea of how others felt about the various responses, and that could add or subtract weight to someone's comments. Keep in mind, my take is flawed because it's based more on my own personal habits when it comes to voting than anything else.

I rarely, if ever, vote negatively, and typicically when I vote, it's more a way of saying, "Yeah.. I found that interesting or worthwhile. I may not even necessarily agree with it, though more often than not it's a vote of general agreement. It's more in line with other sites that allow others to say that they found someone else's comments helpful ("There were X others who found this review useful..")

Is it scientific? No. Is it statistically sound? Again, no. Keeping in mind the numerous and possibly random way in which some people vote, I'm amazed at how often reputation -- most often on some of the smaller threads seems to fairly accurately (IMO) reflect the quality of a node within a thread. I don't think it's ever been the only reason why I've ever looked at a node, but then again, I have looked at some nodes that I never would have seen if they hadn't appeared in the "best/worst" lists, so I guess - yes, in a sense I've occasionally found it useful. That probably doesn't reflect very positively on my judgement, but there you go...

My question to you would be why show this information at all to anyone but the person who wrote the node, if it's so useless? What does the act of me voting positively or negatively on a node have to do with making the information any more or less worthy of being viewed? Just curious, and trying (but failing) to see the downsides of seeing the reputation of a node prior to voting.