"None of us is as stupid as all of us".
Americans are quite unique in that they (especially conservatives) actually believe that each of them could do as well, or better than, our representatives at ordering and regulating society. Because of this trait they tend to relate the business of government to their own experience in actual business and choose representatives that echo that belief.
Our government's purpose is not to be "efficient" in the same way that a business is. It is an entity that solely exists to service society and move it forward as its people evolve. What is holding it back from this (Constitutionally mandated) purpose is the false belief of the population that it functions by the same rules and edicts that work for individuals. Nothing could be farther from reality.
In a "direct" democracy" all of the false concepts and myths of government and economics would become reality and not just political talking points that even the politicians (or at least the smarter ones) don't believe. We'd likely be hampered, once again, by the proven failed "gold standard" because people don't understand a government as the "source" of the currency that establishes the "value" of such things as gold and prefer what they can touch to what is more elusive to the untrained.
Worse yet and more likely, would be the inevitable "balanced budget" amendment that would destroy the economy within a year and leave no "out" to facilitate a recovery. It is a common thread among conservative political thought, just as higher taxation is among liberals, which only shows how disconnected most people are from how the basic systems of our society work and how much their "feels" are more likely to be translated into legislation than economic reality.