Leninism directly reverses fundamental premises of Marxism, including the required initial conditions and path. It's not Marxism.

There has been real Marxism, though it's never been absolutely dominant in any society. Particularly, it has been a key driving force in replacing the system of Capitalism that 19th Century socialists identified and critiqued with the substantially different modern mixed economy as the dominant economic form of advanced societies, even though Marxists would claim that as far from a complete success, as the modern mixed economy is far from their desired end state.