Marx, like Adam Smith and Walt Rostow, had a stages theory of history. Feudalism was succeeded by capitalism, and capitalism is to be succeeded by socialism. Socialism is to arise first in the most advanced capitalist countries. (The theory of history is not my favorite part of Marxist theory.)
Russia, in 1917, was a semi-feudal country with peasants as the largest class. I guess China was the same, before Mao. A Marxist would not expect socialism to be successful in either country.
I think Lenin and the Bolsheviks agreed with this thesis when they first came to power. They expected their revolution to kick off revolutions elsewhere in Europe. And their expectations seemed to be initially met, what with the Spartacist uprising in Germany, Hungary, and so on.
Lenin, knowing that Russia was not ripe for socialism, talked about state capitalism even before the October revolution. Stalin invented the doctrine of socialism in one country. Economic development in the USSR and, I guess, in China, was amazing, albeit with much brutality. But eventually, further development required some semblance of capitalism
Is this not just what a Marxist would expect?
References- Steve Paxton. 2021. Unlearning Marx [I have barely started this].
- Terry Eagleton. 2011. Why Marx was Right.