one liners are usually frowned upon on HN, the logic goes that it just clutters without adding anything to the conversation, if you just want to agree the logic is you upvote. The problem is this creates the perception of downvote being for i disagree which is not truly the case. Generally down-vote should be reserved for useless, false-fact, deceptive or abusive posts. In your particulate case the down-vote was used correctly because the post would fall under the useless (I am not trying to be rude just trying help you understand the logic). So on HN while someone may agree with the sentiment of your post, they may still down-vote you based on those criteria for down-voting. Using the down-vote correctly is one of the things that has kept the HN community from devolving into a clone of many of the other offerings on the internet. It used to be better than it is now, and in my opinion the only thing that has kept some of the quality is the proper use of down-voting to reduce the signal to noise ratio. Over time they have upped the requirements for down-voting, but my assumption would be that the threshold for down-voting is set to about the point where people start to understand the importance of correctly down-voting.
So in short it's not that people disliked what you said, rather they felt that it was not important enough to not be swept away to clean up the signal to noise ratio.