Your questions betray a terrible confusion. There was never a DotP “established” by Marxism-Leninism. There was no such thing as “Marxism-Leninism” when the Bolsheviks siezed power from the provisional government in October. By the time “Marxism-Leninism” was created by Stalin, there was no longer a DotP in Russia as the world revolution had degenerated and capitulated to class collaborationist opportunism. “Marxism-Leninism” is the result of and the excuse for that opportunism and from its inception took the role of the ideology of the nationalist foreign policy of the capitalist Soviet State divorced from the historical communist programme.
Why do you think Stalin need to jail, kill, or exile all the old guard?