It does. Comments have a little "[-]" next to them - click on that and the comment and its tree of descendants collapses. It was implemented nearly four month

It does. Comments have a little "[-]" next to them - click on that and the comment and its tree of descendants collapses. It was implemented nearly four months ago - here's the announcement: https://news.ycombinator.com/item?id=12073675 https://news.ycombinator.com/item?id=12073675