I'm mistaken then; from the block you copy and pasted I misread it to suggest only IE 9 cares about quirks. In my personal use I'd never seen it matter cross-browser before
Of course HN works fine, if it didn't work fine it'd be fixed by now. "Working fine" is an extremely low bar for any site. As a developer you will still want to avoid quirks mode because it just makes your life harder for no reason.