So what do you want exactly? That certain group compositions are not allowed to do enter dungeons? Why not a carpet ban on all mages, as they seem to be involved in all dungeon farming strategies.
As long the certain group doesn’t violate any of our rules, like boosting characters or multiboxing, I don’t see why this is a problem. Doing spell or melee cleave is nothing we don’t allow. It is up to the players how they want to clear a dungeon and maybe find out more efficient or creative ways.