From the end of WW2 until about 1970, the Soviet Union averaged over 10% annual GDP growth, with a savings rate about 50%. By 1970, it had leapfrogged Britain, West Germany and Japan to be the world's second strongest economy.

With good culture and good leadership, Communism can be a brutal success, economically.

Unfortunately, the stuff governments want done is rarely good for human happiness or flourishing.

This is true of every Statist system, not just Communism.

(Communism's failure modes absolutely suck, as evinced by the Brezhnev and Gorbachev eras. But I'm not sure how much better surveillance-centric crony capitalism is with Brezhnev-style fearful ineptitude spreading at the top)