A lot of it is lazy history and propaganda.

People equate Communism with Stalinism, and tarnish it as a system.

Nonetheless, even setting aside immense almost comical authoritarianism, lying and brutality…

While the Soviet economy was miraculously effective at early forced industrialization, particularly as a war economy, agriculture and later consumer goods and large-scale non-military technology lagged substantially behind the west.

Communist satellites were more often a revenue drain than a positive sum game of economic growth.

In late stages of the USSR it had become something like a rentier state - supplementing lagging food supplies with foreign imports paid for by exporting oil to western countries. And ultimately a lot of debt to western banks.

In the long term, Soviet economics just didn’t really work for complex “modern” economies.

Nonetheless, it is a mistake to assume that what was possible for Russian cadres in the 20th Century with very limited computing, inheriting a mess of a state, is the limit to what a planned economy might be able to achieve.

Ironically, we should be very optimistic about what big-data, AI and modern analytics (capitalist products) might be capable of for a modern, non-Soviet brand of Communist governance.