I would like to limit this thread to discussing “recognising and fully implementing ranks beyond 25 kyu”. The other half of the original conversation (9d+) seems to involve different issues.
I’m not suggesting any change to the Glicko2 ranking system. It already goes beyond 25 kyu. We just don’t display it and possibly don’t use it for match-making.
My experiences as an amateur IRL Go coach mirror those expressed by others in the original thread. ie. That there are significant and meaningful differences in the 25k and beyond ranks.
I believe it is possible for a 30 kyu player to remain at that level and enjoy the game at that level and they should be afforded the same opportunities to arrange games (or tournaments) at their level.
Semi-arbitrarily, I’d extend the system to recognising ranks to 35 kyu.
I would be interested to see a current rank distribution graph of “Active non-provisional ranks on OGS” if @S_Alexander or someone else can provide it, to further inform the discussion.