> I mean, Facebook, my bank, Amazon… these can all be created with no client side code. It would be a lot of refreshes, but it can be done.

HN could too - perhaps the biggest use on HN is not refreshing when up (or down) voting something. YouTube could do something similar - refreshing when 'liking' a video or getting more comments. But would you really find those to be a better experience for you? Even on actions that HN does refresh on, such as 'Next page', or submitting a comment, HN doesn't freeze sorts, so posts and/or comments you didn't see will often invisibly end up before the new location HN sent you to (or posts/comments you already saw earlier in the list now showing up "again" later in the list).