Murray Rothbard defines the phrase free market: "a summary term for an array of exchanges that take place in society. Each exchange is undertaken as a voluntary agreement between two people or between groups of people represented by agents."
The fundamental dogma of all brands of socialism and communism is that the market economy or capitalism is a system that hurts the vital interests of the immense majority of people for the sole benefit of a small minority of rugged individualists.
Even a degenerate capitalism produces more prosperity than the best socialism. Therefore, the task ahead cannot be to remove capitalism in favor of socialism but to make capitalism better.
No such thing as a "natural" monopoly has ever existed. In real life, so-called "public utilities" faced frequent competition, so they secured government monopolies to destroy the competition and invented the myths to rationalize their monopoly power.
Although they never actually accomplished it, one of the worst things the Keynesians did was convince some people that they had refuted Say's law of markets.
