Marx's biggest failing was that he did not consider a third possibility: fascism. Such a populist movement was inconceivable to Marx, the epitome of an enlightenment thinker.
What is fascism? Look at the bottom of https://en.wikipedia.org/wiki/Definitions_of_fascism wrt Orwell's comments, and "Fascist as insult".
I remarked elsewhere that the art of dialectic was at some point lost; in Plato's dialogues the method was used to free the other person's soul from contradictions by advancing questioning of their assumptions and models. On mass platforms this cannot arise, as one's reputability (which should be irrelevant) comes into question via the usage of downvotes, and further the downvotes do not advance the dialectic, they aim to put a halt to it. It were as if there were, in the time of Socrates, a man sitting at the table during a diologue who did not engage but merely remarked "That's wrong!" or "I disapprove!".