(Disclaimer: my site)I definitely agree with this, and on Tildes (https://tildes.net) the default sorting method causes topics to bump back up to the top when there's a new comment on them, the same way forums work. We regularly have topics stay active for days or weeks because of it, and old topics will suddenly spring back to life when new discussions start.
Tildes's mechanics have a lot of similarities to reddit/HN-style sites overall, and you can still choose to sort by votes, strictly chronologically, etc. if you prefer, but I've always liked that forum-style method. The heavily time-dependent approaches that are popular now force everyone to need to reply quickly. On HN and reddit, if you don't get involved in a thread in the first 12 hours or so, you might as well not bother because it'll disappear soon. Replying to anything over a day old means that almost nobody will ever see your comment.
Tildes is still young so it's not extremely active yet, but there are usually a few hundred comments and ~50 topics every day. If you (or anyone else reading this) is interested in an invite, feel free to email me. The address and a lot more info about the site is in the announcement post: https://blog.tildes.net/announcing-tildes