The USSR is the only known society to lose around 20% of it's population (and generally speaking these were the most hard core communists) over the course of almost 40 years of continuous warfare (with a small break during the late 30's), lose most of its major pre-war infrastructure, and somehow not slip backwards into a feudal state of being, while competing with, and in some areas, technologically surpassing, a global hegemon who sacrificed far less, and sacrificed none of their infrastructure.

To some degree it is a modern miracle (more of a testament to Marxist theory) it even existed at all, and for as long as it did. And if they had been able to last until the age of the internet, they likely would be where China is now. However, it was clearly too much pressure on too fragile a socialist experiment, and as a result their progression in history has mostly stalled, doomed to be either a gas station for Europe or a boogeyman for NATO. Not a backwater, but the amount of rotting infrastructure in the former USSR really demonstrates how completely ineffective capitalism is at actually serving regular people.