According to Hayek, the Perfect-Knowledge Assumption Has Allowed Neoclassical Economics to Assume Away THE Problem That Needs to Be Explained

According to Hayek, ‘Competition is essentially a process of the formation of opinion: by spreading information…[i]t creates the views people have about what is best and cheapest…’. Moreover, said Hayek, the perfect-knowledge assumption has allowed neoclassical economics to assume away the problem that needs to be explained, namely,

how the spontaneous interaction of a number of people, each possessing only bits of knowledge, brings about a state of affairs [of zero-profit general equilibrium]…which could be brought about by deliberate direction only by somebody who possessed the combined knowledge of all those individuals. 

To show that…the spontaneous actions of individuals will, under the conditions we can define, bring about a distribution of resources which can be understood as if it were made according to a single plan, although nobody planned it, seems to me indeed an answer to the problem which has sometimes been metaphorically described as that of the ‘social mind’.

Hayek’s greatest single contribution has been his emphasis on the market’s role in ameliorating ‘the real problem faced by society’: the imperfection of knowledge and the resultant need for a system which provides incentives for agents to seek and to transmit new insights via the pursuit of profit-making activities.

--Frank M. Machovec, Perfect Competition and the Transformation of Economics, Foundations of the Market Economy (London: Routledge, 2003), 23-24.