The complaints are not unanimous. People from both Aurvandil and Fontan not belonging to the clan have vouched for them, saying they were fun and not exclusive.
BM, however "light weight" it is, depends on hyper active players to make things fun. The rank-and-file sheeple who log in once a turn at best don't make the game fun for others.
These guys are not using their advantages to create stagnation, they are using it to create conflict. If all they wanted was boring control, then they could easily spread out and monopolize a bloc of realms.