Earlier quoted context omitted.
I don't think you're being fair to the community here. It's true that such comments exist, and so do many other kinds. Many users share personal experiences. Many express vulnerability. Self-doubt, questions, and comments expanding on others' ideas are highly represented here, and we value them tremendously. I puzzled for years over why people would say things like "90%+ of all comments" that are so obviously (to me)…
A cynic might say that the content of your comment provides reason to disagree with the previous poster, whereas the comment itself could also be a reason to agree with them. On a more serious note, I wonder whether it has something to do with the fact that on HN it is frowned upon to express agreement in comment form (that's what upvotes are for), however when disagreeing/expressing disapproval, it is accepted pract…
Empty comments can be ok if they're positive. There's nothing wrong with submitting a comment saying just "Thanks." What we especially discourage are comments that are empty and negative—comments that are mere name-calling.