Last time someone tried to host a nation based tournament on Bannerlord, it ended up in lots of defaults due to Poland being a clear victor of the tournament and during the previous stage of the game, almost nobody played except Germany, Poland and Turkey afaik, so I don't see a point in hosting a traditional group stage which would result in exactly the same situation where people wouldn't play and it would end up in the teams just giving defaults after 1 week or so, I'd rather to shorten the tournament initially. I wouldn't mind the group stage as well though, if there would be enough interest voiced about it.