What is your definition of 'Free Market'?
What Adam Smith described in The Wealth of Nations (Which is much better interpreted after reading Theory on Moral Sentiments) is nothing like what is practiced today. Free Enterprise abhors Oligopolies (Monopolies in practice do not exist) and requires a Minarchist or Limited Government. Just enough government to 'help' enforce contracts and property rights, and not so much government that encroaches on contract and property rights. It's the Goldie Locks Zone of Government. Not too much and not too little. It takes some effort to keep it in that Zone.
It is essentially the attempt to integrate Human Behavior and Natural Law.
The Free Market need not be a myth, it just cannot exist under the type of government that we suffer under. That said, if a truly Limted Gov't were to be practiced, the Free Market would spontaneously grow and thrive.