(Wikipedia) Totalitarianism is a form of government and a political system that prohibits all opposition parties, outlaws individual and group opposition to the state and its claims, and exercises an extremely high if not complete degree of control and regulation over public and private life. It is regarded as the most extreme and complete form of authoritarianism.
In a utopia where you have a perfectly benevolent leader an autocracy would be great. My point is power attracts unscrupulous people which given enough time will shape policy to benefit themselves and consolidate power if there aren’t safeguards in place.