Free markets cannot restrict competition, by very definition they are free. What you are referring to is a trade guild, which can only exist in a market that is at least partially controlled by the government. The post civil war “gilded age” in America was hardly a libertarian utopia. The national government hotly debated issues such as tariffs and free-trade, while corrupt political bosses bulldozed the regulation of business. The concentration of wealth that resulted was because of the ownership of capital goods, such as railroad, and steel, by a small number of people.