You're quite right. Arguably, an attempt at formulating an objective morality has been made: https://en.wikipedia.org/wiki/Objectivism . However, it is anathema on HN.
Objectivism has little to do with objectivity, despite sharing the first nine letters. They are two entirely different concepts. Whether objectivism is preferred on HN is another unrelated question.
Objectivism has a lot to do with objectivity. I'm sorry if this is news for you. How reality is perceived and how objective knowledge is attained are at the core of this doctrine -- without these one cannot even talk about rational pursuit of self-interest.
I wasn't even asking a question about HN, just making a remark.