Only he can say whether he has done this out of conviction or in an attempt to garner further support from the Reagan-hating Left. It is this kind of conceit that turned middle and eastern Europe into a vast slag heap and turned once prosperous Argentina into an economic basket case. He showed that in the absence of markets there was no way by which any agency could rationally allocate factors of production. This would eventually result in economic collapse. Mises insight was further expanded by Professor von Hayek who finally brought home the role of the market as a coordinating process so complex in its nature that no mind or agency could ever hope to grasp even a tiny portion of it let alone find a substitute.
Market prices are central to the market process.
It is the information that prices contain that enables the market to carry out its coordinating function. But prices are the creation of human action and, fundamentally, it is human action that is being coordinated. Without the proper signals individuals are being denied the vital information that they need to carry out the necessary daily adjustments and economic calculations that are essential to eliminating diseqilibriating forces. Therefore, distort the pricing process and you misdirect human activity which always results in malinvestments. The greater the distortion, the costlier the malinvestments to society.