Ironically it does exist in places that are communist.
Which kind of brings to the inherent contradiction within communism.
Marx talks about a "dictatorship of the proletariat." A dictatorship implies unchallenged decision making. How can such a large portion of the population hold that kind of power?
Through a "vanguard." It's not really the workers who hold the dictatorial power, but a small group of people led by one person who acts as some kind of "representative" of the workers. This leads to the result of the workers themselves having no real power at all, and instead being under the dictatorship of someone who acts in their name.