[layer8]

One important Usenet feature that enables efficient tracking of and participation in discussion is that read/unread status is tracked per posting. (See my related comment in the sibling subthread.) That kind-of requires keyboard navigation to make it practical (e.g. press Tab to jump to the next unread posting, which then automatically becomes read). But keyboard navigation by itself also tends to maximize usability for frequent/regular users, which I'd argue are the important demographics for discussion forums.

One issue is with mobile UI, where there's really no good way to make per-posting read/unread status practical with just touch (and/or voice) input. But I'd also argue that asynchronous discussions (as opposed to chats/IM) are best performed on desktop. On mobile they will always remain a compromise in usability and content quality.