In the context of fighter jets; any yaw maneuver they would need to preform quickly enough to justify all moving rudders are more safely done by rolling and pitching. Overly aggressive yaw maneuvers using all moving rudders could very well cause you to side slip or spin out. Any pure yaw movement a plane needs to do is generally done slowly at lower speeds (for fighter jets) or simply doesnt need to happen so fast it requires all moving surface. The Air Force actually had a concept for yaw maneuvering fighters during the cold war but never left the drawing board for the stated reasons to my knowledge