My Caveman explanation stands
Oh, and BTW, as for "caveman" proxy for barter -- something that seems, by dint of how much you keep mentioning it, strikes you as a stroke of genius -- it "stands" in your mind only (one hopes) because you've made no rigorous effort to understand (rigorously analyze, compare and contrast) the
development of money, and therefore also its attendant banking system, as a medium of exchange.
Even economic scholars who are not apologists for and adherents to the orthodox story of the evolution of a fixed medium of exchange, money, recognize that regardless of one's POV about the merits and demerits of money and a central banking system it's vastly more efficient, thus economically better, than a barter based system used for exchange both inside a given political economy and with parties in external economic entities.
Money was not injected into a well-functioning barter economy; instead, money and the market developed together. This helps to explain why production in a market economy is always monetary production: money now for more money later. It also means that the money supply in a monetary economy is necessarily endogenously determined. Monetary economies have not, and cannot, operate with exogenous money supplies. Finally, while a monetary economy with an endogenous money supply can operate with a commodity money reserve system, such a system is subject to periodic debt deflations.
Thus, in all developed capitalist economies, this has been replaced by an accommodative central bank reserve system. The Monetarist policy prescription (close control over the quantity of reserves) represents a giant step backward, to an unstable system in which accumulation suffers occasional reversals during debt deflations. Furthermore, Monetarist policy would not lead to greater control of the money supply--the supply of reserves (whether of wheat, of gold, or of central bank liabilities) has never determined the quantity of money. Rather, rigid control over reserves would eliminate the primary advantage bank liabilities have over other types of liabilities and would lead to greater use of alternative money-denominated liabilities. This, however, comes at the expense of the revival of debt deflations.
While a commodity reserve system is possible, it is far more unstable than a central bank reserve system. Rather than attempting to constrain the central bank so that its liabilities are supplied as if we had a commodity money reserve system, it is far better to maintain the current accommodative reserve system.
Truly, I had no desire to address barter, as it really doesn't factor materially into the American economy's manifestation of unrestrained capitalism, but you proudly (?) mentioned it so damned many times, I figured I'd be courteous enough to remark upon it.