It didn't necessarily bring anything to this one conversation. It did, however, communicate that "this is the type of information that that person finds valuable on Hacker News". And knowing what other people in your social group like to hear/discuss is an important part of keeping that group vibrant and wonderful.

So no, it's probably not as useful as the comment it was referring too, but it was useful (to some of us) as it pertains to the community as a whole.