As a few other HN participants before me have done, I note previous submissions (when I notice them myself) partly to figure out the vagaries of the duplicate thread detector here and partly to keep the emphasis here at Hacker News on new stories. Some old stories are very worthy indeed of further discussion, but looking at previous threads and their level of discussion can help busy HN participants who didn't notice the last thread(s) decide how much new discussion to engage in about a previously submitted story.
That would be useful if either of those had comments, but it doesn't look like much of a discussion occurred on either. So I think this merits a repost and I can't say I understand the purpose of commenting to simply link to no discussion. Maybe you could enlighten us as to why you do that?
Edit: I see four comments in the link you added in edit. Unfortunately I find these kinds of comments to be a distraction; they don't actually add value to the discussion and instead contribute one more thing that must be filtered and often ignored. In the cases where there is significant discussion, it can be useful. But all too often it comes across as condescending and does little to actually build upon a new discussion.
http://news.ycombinator.com/item?id=3349461
http://news.ycombinator.com/item?id=3355254
AFTER EDIT: Oh, and the previous submission with the most comments:
http://news.ycombinator.com/item?id=3350529
As a few other HN participants before me have done, I note previous submissions (when I notice them myself) partly to figure out the vagaries of the duplicate thread detector here and partly to keep the emphasis here at Hacker News on new stories. Some old stories are very worthy indeed of further discussion, but looking at previous threads and their level of discussion can help busy HN participants who didn't notice the last thread(s) decide how much new discussion to engage in about a previously submitted story.