> we started searching for a tool specifically built for complex discussions. We found none
This was basically solved in Usenet, more specifically, in news reader software. You had a clearly arranged threaded view (you could see the thread structure of as many as 50 postings on a single screen), with unread threads and unread postings highlighted, and pressing Tab jumped to the next unread posting. Unread status was per posting/comment, not by time. Many more conveniences for quick navigation, filtering, and so on.
All newer discussion platforms have been a step back in terms of efficiency of use and ability for deep, long running discussions. Initially due to web browser limitations (though nowadays that shouldn’t be much of a problem anymore), and later due to mobile touch interfaces (still poses some difficulties).
This was basically solved in Usenet, more specifically, in news reader software. You had a clearly arranged threaded view (you could see the thread structure of as many as 50 postings on a single screen), with unread threads and unread postings highlighted, and pressing Tab jumped to the next unread posting. Unread status was per posting/comment, not by time. Many more conveniences for quick navigation, filtering, and so on.
All newer discussion platforms have been a step back in terms of efficiency of use and ability for deep, long running discussions. Initially due to web browser limitations (though nowadays that shouldn’t be much of a problem anymore), and later due to mobile touch interfaces (still poses some difficulties).