I liked it for the sheer level of awesomeness of investing work to analyse comments, and I like the reminder how really chaotic stuff can be quantified as well, but I find comments not really that important, important stuff tends to be rewritten as a post, so I treat them more as just a discussion. Similar to chatting about a post in person.

However if you want to know the usefulness, I think depends on whether you care about upvotes. I care about them only in a negative way, I tend to recycle usernames on Reddit when they get too much karma although I have not done it here yet.

I don't think if I would optimize my upvotes it would also result in optimizing the usefulness of my comments for others. If anything, the number of replies I get is a better measure, blatantly stupid stuff usually gets ignored, if something gets answered a lot then at the very least it is wrong in an interesting way.

I mean, for example here, I think the fact that I reply to your post and survey hopefully means more to you than if I just hit the upvote button. Same story.