I get it, we love the nostalgia of something ancient persisting into the future, but a couple lines and a @media query could kill the needed pinch and zoom on thousands of phones a day.
Well, there's a plethora of HN apps, if you really really want a mobile experience. I'm actually super-happy I don't have to 'request desktop site' when I go to HN on my phone to get a non-responsive site.