I am a long-time user of both flat and threaded discussion forums. I run a 15K user group on Facebook and know their threaded system well. In reading this topic, I feel people are not thinking clearly about the issue of flat versus threaded discussions.
First, these are never mutually exclusive methods of organizing a topic’s replies! Threaded discussions are simply a VIEW of information. Discourse has the information about which posts are replies and could construct a threaded view of the replies. There is no reason in principle that you could not simply have a UI that lets a reader select a flat or threaded view of any topic, and change that view while reading it. So it’s simply silly to discuss this issue as if you have to choose one way of organizing information a priori.
Second, I think if we asked one million people whether they preferred flat of threaded discussions, more than 80% would vote for threaded. It’s distasteful to hear the 20% that insist on flat discussions ignore the desires of most users, when the fix is actually just a straightforward UI selection, as I already described.
Third, the value of threaded discussions in a long list of replies is to help someone save time. One use case alone should give an example. Say that we are discussing the use of a prebiotic fiber in the diet to encourage the growth of a specific species of bacteria in the human microbiome. A user from Australia asks “where can I buy this in Australia”. That starts a sub-thread of 50 replies from Australian and Asian users. I am not from Australia. I don’t have interest in this sub-thread. Why make me read those 50 replies? Threading gives me a convenient UI to bypass irrelevant subtopics and lets me focus my time on what I care about.
Now it’s true that this information could have been started as a linked Topic. It’s also true the moderator could have moved out the information to a new topic. But that doesn’t usually happen. In my forum, I barely have time to respond to users. I definitely don’t have time to spend all of my day micromanaging the structure of every thought every user has.
Some day in the future, I would hope that Discourse would stop belittling 80% of the users who want threaded discussions, and just invest in a UI that lets each person make a choice.