Socialists, communists, nazis, fascists, and any other variation of socialism that has been inspired by Marx, all despise the free market soooooo but they have no understanding of what it is.
A free market economy (or as Marx called it, capitalism) is just as simple as the socialists described it in their tweet on Twitter. It is just the free exchange of a product or service for another product or service. The exchange can be a barter or it can be done with currency, it doesn't matter. And that is all it is. It is nothing more and nothing less.
Marx spent his life trying redefine free market economics into something evil, but the problem was that Marx, himself, was an evil and corrupt man who hated mankind. He hated Jews and, like Hitler, was a Jew. He hated blacks and only referred to them as the n word. In his spare time he wrote love poetry to Satan. In the end he had alienated himself from his wife and children and died a lonely, penniless, wretched man.
A corrupt man cannot possibly device an economic system that is not corrupt.
Jesus said, "Beware of false prophets, which come to you in sheep’s clothing, but inwardly they are ravening wolves. Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles? Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit. Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them." - Matthew 7:15-20 (KJV)
The fruits produced by Marxism are genocide, torture, slavery, misery, starvation and extreme poverty.