It is the tersest way imaginable of saying that Jesus Christ is sufficient. He does not need to be supplemented. As the revelation of God, as the guarantor of our restoration from the ravages of sin and affliction, he is sufficient. All the thrones, dominions, principalities, and authorities are to do this. Nevertheless, like everything else in a fallen world, they are fallen.
Civil government is divinely-mandated to prevent social dissolution and secure justice.
No government at all would guarantee chaos. Human existence is impossible amidst social chaos. Life under a tyrant may be thoroughly miserable, but at least life is possible. And however bad governments might be in Ottawa or Queen's Park, they are preferable to Saddam Hussein, preferable to Moamar Khadafi, preferable to Josef Stalin or Chairman Mao. Yet because the principalities and powers are fallen governments work evil as well.