[grufus]

Rather, the result of sanctions, i.e., the almost total absence of cross-border trade.

Historically it was through trade that societies/nations became successful, were growing, were eventually dominating. The early dominance of Europe was thanks to its long coastal lines, allowing to quickly connect to neighbors and thereby exchange goods, thus trade. The industrialization was kicked off in Great Britain, the culmination of extensive trade combined with the abundance of cheap energy (coal + steam engine). Which then took off in all of Europe, again trough trade.

If you artificially limit trade of a country, either externally because everybody hates you, or internally because you are crazy, then you automatically limit your development and thereby growth. Communism or not.