That seems.... not true. HN doesn't actually send the page. It just gives the URL that lets me go to that page. Then another server sends it. Or at least tries. Sometimes the traffic is too much and the page goes down. In that case HN is very much not responsible for sending the page!
Except when they don't.<p>Because, sometimes, they won't.<p>I'm sorry to say so<p>but, sadly, it's true<p>that unknown<p>or expired link<p>can happen to you.