All governments oppress people. The real issue is to what extent they do so and what fraction of the people consider themselves oppressed. Unfortunately the frontlines after WW2 where redrawn and Czechoslovakia was in the unenviable position of having to defend the Warsaw Pact while its population wasn't fully supportive of this position. Those who opposed (anti-Stalinists) were oppressed. As a mirror image, consider Greece where pro-Stalinist communists were oppressed in 50s and 60s.
