Probably the same reason T~F are having problems with billybigballs. (and he only has 900 points) and they have over 100 members. In both cases they are not capable of nobling an active player as they are serial barb noblers.
Without trying to bring Bi into another thread I do wonder whether by having all the better players from the start has meant other tribes are made up from noobies with poor/no leadership
On W1 for example all the good players were spread about over several tribes which allowed them to develop into decent tribes, giving the world a number of well run tribes. Yes most of the better players on there have now grouped together in W1N but this has been over several months.
Because Bi started this world with most of the better players it hasn't allowed many other tribes to establish with decent leaders.
Hence a number of tribes who can't even handle a single player
Vibe? have good leadership and everyone is very active, we seem to be doing pretty well and we all get on with each other, yes we have some less experienced people in our tribe but yet we have some very experienced people in the tribe aswell, so i wouldnt say all the best players are in Bi!
Sparticus was a member of the HEROES - he put someone as sitter but never came back. The sitter built up the village all the way then just before the sit duration ran out he passed to to someone else for 24 hours and Nobled it.