One (single) Party System = In totalitarian states, a monolithic organization parading as a political party performs a wide range of functions, including political recruitment, indoctrination, mobilization, and surveillance (Nazi Germany, Soviet Union and China)
Most are associated with dictatorships!
Democratic one-party system are rare and often wide open to corruption.
A virtual monopoly of political power encourages cozy arrangements among business leaders, bankers, entrenched bureaucrats, and top government officials.