Comments that don't add anything (extra information, or point out a problem with the article) tend to get voted down. "I liked this" is not considered a valid comment on HN.

I knew it would happen anyway :) Probably the only comment I've made on HN where I knew beforehand that mentioning WOW would instantly attract the down-vote hammer. (I don't even play it any more, but knew if I mentioned that tidbit of information as well, I would get downvoted by people who don't play WOW, and people who play WOW now. ha).

<meta> Short of snark and obvious trolling, worrying about downvotes is counter-productive. Some people may downvote posts such as your jewel comment due to the potential for sidetracking the discussion into something generally outside the interests of HN. On the other hand, such a post may trigger an "I never thought of it that way before" reaction.