Alternatively, one could argue that postwar prosperity was strongly correlated with friendly diplomatic relations with the US, the only major world power that didn't have its entire industrial capacity reduced to rubble during the war. Saying that the Eastern Bloc countries floundered solely because of a lack of a free market when they were militarily occupied by a disastrously incompetent foreign power sounds like an oversimplification to me.

It was more about central planning, collectivisation of private property, and lack of management (directors where assigned based on politics), than occupation by force. Austria was under soviet occupation till 1955, but they were still lucky to become a free market country afterwards. Romania was occupied till 1958, Hungary from 1956, Czechoslovakia from 1968. Poland and Bulgaria were not occupied after 2nd world war, but their economy was still in shambles.