This is meant to represent the concept that great strength comes from many bound together in a single purpose. Where one would be too weak, all together are capable.
And diversity is the antithesis of working together for one unified goal. The various groups' lack of any agreed upon culture or standards other than a shared marketplace means that the government must regulate ever more elements, and must enforce those laws and rules. The governed no longer agree sufficiently for the phrase "consent of the governed" to have meaning. And thus we may be destined to descend into empire, and thence into tyranny.
Further, an outside force may enjoy the aid of a fifth column already in place within the US. We see at least the suspicion of such a possibility with moslems in the post 911 world. This too weakens us - especially if we face an enemy with a large domestic constituency.
It is the root word of fascist and fascism.
I'm not making any political point here. Just thought you should know.