In fact, China, the fastest growing nation in the world is Communist and doesn't let free markets roam "freely."
I don't know what the correct economic system is. If we did, that is what would be implemented world-wide. Pure Capitalism is almost certainly false thought. And so is pure state control.
China runs a hybrid Mercantile-Capitalist economy, with heavy state protectionism of certain key industries. It's totally different then Cuba and the old USSR which was top-down, command-and-control economy.
