Russia. China. The assorted satrapies of Asia. The caudillo-controlled regimes of Latin America. Even colonial regimes administered by nations that were democracies at home have turned to socialist dictatorships if the colonies were exploited for their resources rather than educated to the ways of democracy. There was even a Commune in Paris for a little while, in the wake of Napoleon III, who was neither a socialist nor a liberal.

People governed by leaders subscribing to an extreme philosophy are more likely to swing to the opposite extreme. Any intervening time of self-organizing or self-government (including opposition trade unionist movements like Solidarity) are prone to mitigate the extremism.

Not all undemocratic governments are socialist. Not all socialist governments are undemocratic.