While this heavily depends on the user group bug trackers make it easier to self-organise topics. A few open-ended issues for general chatting (or some other platform of your choosing for that, discord or whatever) but more narrowly defined issues (be it a bug, be it a suggestion for improvement) get a new ticket number and are tracked separately.
With this the general discussion is not cluttered with solved stuff and an idea graveyard but one can still point newcomers to it - often faster than to answer the same questions for the umpteenth time.
A typical use case is balancing: The planned combat system *will* need to be revisited quite often, and instead of discussions all over the place (see page 1, 4 and 16 of the forum thread "Rewind 0.2" and yesterday's night discussion in IRC) all comments and suggestions are tracked in #0815.
My 2 cent : )