Russia and China went from backwards shitholes to world powers
This is simply inaccurate. Russia under Tsar Nicholas was a failing power but it certainly wasn't a "backwards shithole" at least not when compared with any other European power. In fact, it was the victory of the Japanese in the Russo-Japanese war that caused European forces to re-evaluate the whole of the Pacific Rim- after all, it was just presumed that Western powers would always dominate Eastern powers. Shifting power from the monarchy to the Bolsheviks had the principle effect of changing who were serfs and who were aristocracy. It did not cause any great advancement of Russian culture or thought.
China, for its part, was an ancient dynastic culture that valued stability over change. When it interacted with world powers that valued innovation over stability it lost. China has always been a cosmopolitan coastline with a rustic interior and China under Chiang Kai-shek was every bit as modern as any other Asian nation (with the possible exception of Japan, which pushed into modernity with determined zeal). Mao Zedong's "modernization" of China plunged the nation into famine; order could only be maintained through totalitarianism. What we consider "modern" China only began with the market reforms of Deng Xiaoping from 1979-on.
Tricky thing about communism (and I'll bet bfv can totally school me on this) is that it has never really been applied to any group of any real size. Soviet "communism" had a lot more in common with fascism than actual communism. Chinese "communism", for its part, was more of an antiintellectualism than an actual communism (see also: the Khmer Rouge).
In each of these cases, shit has gone decidedly south. It's one of the things that keeps the hopes of communism alive - everyone who has ever tried it has ended up fucking it up past the point of recognition.
PIketty, after cranking through 900 pages of powerpoints and algebra, basically argues that the best government for the people by the people is a bunch of socialists reining in a free-market capitalist economy. Because really, that's the happy medium: provide enough freedom and challenge that strivers can get ahead, but nerf the field enough that laggers don't inherit a dystopian hellscape. Really, if you rule you should be better off than if you suck but if you suck, your suckitude should not be visited on every proceeding generation of your offspring.
And that right there is the tricky balance of all of human society: balancing the needs of the strivers against the needs of the laggers. I'll be the first to observe that things are way to far into the striver camp at the moment.