alt Hacker NewsBut replies in forum topics weren't a single chronological conversation either. Especially in those huge threads with many posters. It was people replying to posts who knows how far back in the stream, maintaining a bunch of smaller conversations, or just interjecting a top-level comment based on the 1st post or title.
The upside is that ideally these subconversations can split and merge into a larger conversation. But then you also have the problem of 99% of a topic's history being fluff nobody is ever going to read again, especially not in that 20 year long topic. It only created the illusion of a convo people would follow because it was a stream of posts with a reply box at the end.
Of course, I haven't seen a solution that addresses both sets of issues between tree vs. forum linear pipe, though I think the tree maps better to human interaction and attention.
You bring up an upside of the forum style topic though: the chronological view gives it more lifespan since new posts are given maximal visibility.
On the other hand, long threads pick up too much baggage nobody is going to read, so I think creating new Reddit submissions with fresh participants is better for conversation. The limited lifespan is a feature.
The idea of "dupe threads" never made sense when the "dupe" is a 30 page topic from 6 months ago. We're here to talk and exchange our views, not scan for our views in a conversation others already had. That there could be some sort of canonical discussion or master thread on a topic was probably the worst superstition had in the forum era.
>On the other hand, long threads pick up too much baggage nobody is going to read
I think the key here is, if you don't want to read what other people have to say, why are you here? Suppose it's a discussion on a technical topic. Maybe people have gone off on a tangent that should have been split off into a new thread/topic, or maybe the discussion being had is necessary context to get an idea of where the real answer lies. Reddit-style threads make it easy to have back-and-forth discussions, but at the cost of punishing long discussions with less visibility, or even with worse UX (given the increasingly narrower horizontal screen space as the conversation goes on).
Honestly, want to know who actually has this figured out? 4chan. See a comment, besides it inherently linking to the comment/s it's replying to, you can see at the top of its box a list of child comments that have replied to that comment, and if you hover over the links you can get a quick view of the comment to decide if you're interested (before committing to changing the scroll position), but comments are still listed chronologically, so if you just want to see the newest comments on a thread, it's still possible to do that. Famously, few years ago a stickied thread on /trash/ went on for months and tens of thousands of replies. Something like that would never work on Reddit or HN. Well, I mean, people can still make top-level comments, but after a while no one will see them.