Historical determinism, or the idea that history somehow has a natural ("scientific") direction of its own, is an old Marxian fallacy. History doesn't decide anything, people do.
And Reagan was not only one of such people, in the case of the coup de grace dealt to the Soviet system he was DA MAN.
It wasn´t that bad at all that the left here got a chance to govern.
Ever after the WW II the Left were the real elite of West Germany, with a status similar to that of aristocracy of the time of Frederich the Great. Their very specific, German kind of Marxism was regarded as true polar opposite to Nazism.
Etablierte Linke dominates German universities, where it repoducts itself and populates the offices of the country with its disciples whose main political task is to uproot 'reactionary ideas', that is any conservative or right wing ones.
You see, they still believe in Germany that Nazism and fascism were extreme right movements. In reality however they were... er, read my tag-line.