That is true with active and big chats, like yours I would guess. But I’m not sure if that is general reality? But again, if forums have ability to choose, per channel would be the best working option but forum wide would work too, that would be acceptable too.
The issue with threads is it forces jumping here, there and everywhere and an user must remember to answer to message, not in channel. Same question that with posts in topic, but there that isn’ any issue because it is flat. On other side, topics are quite same thing than a chat message, but UI is fundamentally different.
Sure, it leads another setting and we have already a lot of settings everywhere. It isn’t a nightmare yet, but can be at some point.
But as one of my users said: she wants to see and read everything and with threads she must jump in and out and quite fast she is totally lost what she had red and where she is.
I’m totally sure that more… organized and more flow chart minded users, as devs 
, like threads, but ordinary non-tech ones who haven’t ever used Discord etc? Not that much.