Clearly, you're incorrect, because several people have explicitly stated that they appreciated the mention of this site (and probably there are more who were glad to find out but didn't comment). `bemmu`, Candy Japan's founder, also positively responded to the comment in question.
In my opinion, downvotes on HN should be reserved for malicious comments like trolls, ad hominems, off-topic spam (real spam, rare on HN thanks to the mods. not just "I don't like this comment and think it's off-topic"), factually incorrect comments, and "reddit style" humor.
Users should not downvote comments they simply disagree with, on-topic promotional comments, and tangentially related comments. Tangents are a great way to discover new ideas.
However, there is a small cadre of HN downvoters who disagree with me, and who rabidly downvote any comment with a whiff of being off-topic or controversial. These downvoters must spend lots of time on HN, since their downvotes always come very quickly after a comment is submitted.
Luckily, they do not represent the majority of HNers who can downvote, since comments like this one typically crawl back up into positive territory after the first 30-60 minutes. Some of my comments that were initially downvoted for being "off-topic" even crawled back up to over 10 upvotes.
To the GP commenter, please don't get too frustrated. It's a relatively small number of people who downvote useful comments like yours. It's true that they are among the first to vote on comments, but almost always their downvotes are reversed after some time.