I never said they were not fair examples. I consider them to be successes. I'm saying the dictatorship of the proletariat is necessary in each state where socialism exists until capitalism has been vanquished. This stage is necessary to defending the gains made by socialism. I tried to explain what happens when socialists refuse to defend the gains of socialism from the bourgeoisie. Counterrevolution and extermination. This has happened so many times it has almost proven to be a truism.
I think people refuse to recognize that the history of mankind is the history of class struggle. We cannot pretend that the bourgeoisie, once overthrown, will simply roll over and accept the new order. They will fight to the end.
I do not accept your premise that socialist countries were 'failures'. The system worked so long as it was implemented. Gorbachov and his allies admitted that they sought to destroy the USSR. You cannot say that the system is inherently unworkable if people within the leadership deliberately sought to destroy it. There was nothing 'inevitable' about Gorbachov's destructive policies. The system was working quite normally prior to his radical policies. As people around during the time attest, there was no upsurge in discontent, in consumer satisfaction. The economy had actually improved since the early 1980s. People were eating better than ever. There was no "food shortage", as propagandists like to claim.
Without the military support of the USSR, the central European socialist countries, particularly East Germany, were sitting ducks. Everyone admits that the East German economy did very well, and the standard of living was on par or higher than many western capitalist countries. This is despite the fact that they had serious disadvantages in their development.
1 - They and they alone had to pay reparations to the USSR for WWII (more than $5 billion), West Germany paid next to nothing. East Germany was deindustrialized after the war.
2 - West Germany was the beneficiary of the Marshall Plan (itself a violation of WWII agreements). Money poured in to rebuild West Germany. No such money poured into East Germany.
Yet East Germany prospered. It did not collapse, it was annexed and dismantled. With the Soviet withdrawal of military support there was nothing would defend it from annexation. The industry of the country was wholly privatized. The currency was deemed worthless by fiat. This cannot be deemed a 'failure' of the system anymore than the conquest of France by Germany can be deemed a 'failure' of liberal democracy.
There was a cascade of counterrevolutions after Gorcachov's "reforms" because of the interconnectedness of the Comecon system, the liberalization of the migration regime, economic sabotage from the West, and because Gorcachov's withdrawal of military support emboldened counterrevolutionaries in each one of the central European countries. Socialist leaders, far from being bloodthirsty, decided to surrender to these counterrevolutionary putschists rather than risk civil war.