Marx opined that certain material conditions had to be achieved before a socialist state could be successfully made. These material conditions include bourgeois capitalist democracy. Marx explicitly said that capitalism forges the tools with which it will be destroyed.
A certain subset of communists known as Marxist-Leninists decided that bourgeois capitalist democracy wasn't necessary if you just oppressed people REALLY hard, you could skip straight to a socialist state. And because they 'succeeded' in overthrowing traditional Marxists in 1917 Russia and getting the full power of a massive country to spread their ideology, they've had bootlickers calling their particular brand of insanity the only 'real' form of communism ever since.
When we think of 'communist' countries, we think of Marxist-Leninist countries which tried to jump from feudal societies to socialist societies, which, quite obviously from the results, doesn't work. Doesn't stop the cultists from licking boots, of course.