Well, this theory is easily refuted by the fact that there are governments that have the same degree of power and control over the economy and don't wreck the economy. Some governments cause hyperinflation, but most don't, even though all are in control of the money supply. The fact that a government can mismanage the economy doesn't mean that it will mismanage the economy. In fact incompetent governments such as the Argentinian government are not that common. In many parts of the world the rule is for governments to be competent, or at least to be competent enough to not cause an economic catastrophe.