Nexon is constantly trying to equalize the balance but still gets an imbalance of troops. Prohibition of armies consisting of one type of troops (only Bazooka, only heavy tank, etc.) will simplify balancing. Previously attacked with the crowd of English archers, then heavy tanks crowd, now the crowd bazookas... who needs it? Also need to ban 8 fighter, enough 5.
Ha ha! What I said! See Bastions v7.1 Update Balance Changes - Assault Rally. We didn't have to wait long. AR suffered the same fate as Decoy before and so on.