It doesn't matter if its a dupe of something everyone missed before and people up vote it this time. So much stuff gets submitted now that links are only on the first page of the new list for a few minutes and can easily be missed. This time its hit at the right time and there could be a good discussion about it.
(He's being downvoted because it didn't add anything to this discussion, and it seemed like a case of sour-grapes because he originally submitted the link.
If there was discussion on the original submission it would have been useful)
My comment was posted when this page had no comments, nor was it on the front page. In fact, I think it had less than 3 or 4 points. I was just informing the original poster, given that I too thought it was an interesting article, that it seems there was little interest here on HN.
Clearly, due to getting enough karma to put it on the front page this time, my comment is indeed now irrelevant. The post was clearly just missed the first time as you say. Whether this is a problem with the karma/new post system or not is a different matter - and probably not one for discussion here.
I didn't think I'd get downvoted though, given when my comment was made, but your points are fair.