It is
(See what I did there? I responded to an unsupported statement of fact with another unsupported statement of fact. Both our arguments are equally valid, i.e. not at all. Perhaps next time you post on HN you could add some arguments to support your position, if only out of courtesy to those of us who cannot read your mind to see the no doubt infallible logic behind your opinion.)
1. This kind of response (along with the kind that I am giving now) is often just as much a problem as the initial non-useful post in terms of "useless thread clutter". Things could go either way on whether it's really useful to point out the situation to a user "for their benefit" -- the voting system exists partly to let us wash unproductive responses out of sight.
2. You particularly noted "next time you post on HN", and that made me feel a bit sick. There's little more elitist than saying to a newbie that they need to change their behaviour "around here", or "to hang out with us". It shows a greater concern for our little clique than for the ideal of argumentation, or for the dissemination of knowledge to people who could use it.
All that said, I'm clearly not following my own advice here -- in my defense, I'm making the bet based on your post that you're someone willing to consider your actions and either respectfully disagree or change, but I could be wrong. My response likely ought to be voted down as further useless junk.