Imprecise definition aside, revolutions have to be able to defend themselves, and it could be argued Catalonia and Ukraine started in much better material positions and ended up falling apart because of problems with their political/economic structure, while the semi-centralized democracy and rationalized economy of the USSR allowed them to succeed in defending itself from the Nazis (but not, ultimately, from the US empire, however Vietnam, Cuba, laos, and China succeeded, and the DPRK partially succeeded)