Remember that growth is relative. GDP per capita in the mid 30s was still three times higher in countries like the states, UK, and Switzerland compared to the Soviet Union. This trend continued into the next decades. Pretty much all of Europe had a stronger economy.
And how did that pan out for high GDP France? GDP per capita is a bad statistic to use. Two economists trading a random object and 20 dollars back and forth raises the GDP of a place by forty dollars per cycle
And there weren’t mass famines and rampant scarcity issues to the same extent in the west.
Thats because they exported their economic problems to the colonies. Look up how many people starved to death In British colonial India. Also the soviet union ended the previously periodic famines when their collectivization policy was fully implemented
Yes the Soviet economy did grow, but the libertarian argument is about efficiency.
What sort of efficiency? Because Marxists argue that capitalism is really good at making profit and really bad comparatively at efficiently improving human outcomes.
But many factors influence price (competition from profit seeking, availability of resources, etc).
That is literally why it has low information value.