Marx's theory resulted in much slavery worldwide. The problem with communism is that the state doesn't just own all the property, it owns all the people. Even the ones who do not wish to be owned by it. Once you allow people to own all the industries you need to survive, they own you. "Citisen". Capitalism doesn't rely on authoritarianism. Quite opposite. It relies on free trade. The market. The free choice of people to participate in it.
No, it was the specific implementation of his work that resulted in whatever it resulted in. Marx didn't lay out how to do anything. He produced a critique of capitalism. Define "communism". You're using the word. Define it. You made that up, although it applies to capitalism pretty well. That has never existed. From the beginning capitalism has always been regulated somehow. And there is very little "free choice". To live in society you have to either be a capitalist, or a person a capitalist exploits.
wrong of course he said " workers of the world unite, lose your chains" and they did and 120 million slowly starved to death thanks to the Nazi marx