What is prevented through the expression of different points of view in government?

While the formal separation of powers promulgated in the Constitution and explained in the Federalist remains, and in some respects continues to function well, the actual distribution of powers has changed dramatically.  Congress has become increasingly energetic and administrative, the judiciary willful and legislative, and the executive (in its institutional, not electoral, connection) tentative and judicial. Under these conditions, it is the Congress's and the Supreme Court's power that have grown at the net expense of the President's. But more important than the balance of power between the branches is the maldistribution of powers, the mixing and confusing of governmental functions, which has resulted.

I'll go with that