Totalitarianism is important in some settings because it gives the power to the government, the military and the political parties. It does not allow one single person or single unit complete control over all of the governmental issues.
Totalitarianism is different than democracy in that it does not allow a lot of input from the citizens of the country. Their opinions matter only if they are in agreement with the national political party or with the government. In a democracy, citizens are given the choice on how they want their country to be run and how they want to be directed.
Nazi Germany is an example of totalitarianism being used to influence an entire country. Hitler was a charismatic individual who had the majority of his country convinced to follow along with his beliefs. He had a strong political party backing him and made sure that the party stayed on his side by using fear tactics. Hitler also had a strong army that was able to enforce anything he said. These three factors, in combination with the pressure for a better country for the Germans, allowed Hitler's society to become one of the most prominent and influential totalitarian societies in the world.