Communism is, he explains, “the positive transcendence of private property, or human self-estrangement, and therefore the real appropriation of the human essence by and for man… the complete return of man to himself as a social being…” (Economic and Philosophical Manuscripts of 1844)
Innumerable social thinkers disagree with much of Marx’s thought, but praise his reflections upon human freedom, the depth of his insight in contrast to the shallowness of liberalism. Yet it is difficult to understand how Marx’s concept of freedom is anything more than a defense of tyranny and oppression. No dissident or non-conformist can see society as the “realization of his own liberty.” And what can the attack on “the right to do everything which does not harm others” amount to in practice, except a justification for coercing people who are not harming others? The problem with “broad” notions of freedom is that they necessarily wind up condoning the violation of “narrow” notions of freedom. Under “bourgeois” notions of religious liberty, people may practice any religion they wish (“a private whim or caprice” as Marx calls it); how could this liberty be broadened, without sanctioning the persecution of some religious views?
It’s a stretch to equate ‘social being’ and ‘realization of his own liberty’ with tyranny and murder. Imagine someone wrote ‘I envision a world of happiness,’ and someone upon reading the quote uses it to justify murdering someone, and then that murder is equated with the otherwise pithy quote to have a world of happiness, some must suffer to get it!…He’s obviously advocating murder and tyranny! The logic does not follow.
The passage is possibly also an example of hindsight bias, because by knowing beforehand that Marxism is associated with Communism and death, one is more inclined to interpret anything by Marx as predictive or condoning of violence.
That’s not to excuse Marx…many of his ideas and prophecies were wrong (such as the widely discredited labor theory of value, oppression theories, capitalism being self-limiting, etc.), but you can’t just take an otherwise vague quote and twist it to conform to your preexisting ideology, just because the originator of the quote is associated with some horrible things.
Consider Nietzsche…some say he inspired Hitler, and on the other extreme, Foucault. Both men, to some extent, derived inspiration from Nietzsche’s work. Does that mean we do away with Nietzsche, because of Hitler. Polar opposites (Hitler and Foucault) can find value in the same philosophical work, because philosophy, unlike politics, lends itself to greater interpretation. Philosophy offers insights into the ‘human condition’, existence, meaning, purpose–things that are more universal than fitting squarely into a simple left/right dichotomy.
Postmodernist ‘exploitation/power theology’ is been used both by the far-left, and to a lesser extent, the far-right (political horseshoe theory).
Hitler is quoted as saying “Do not compare yourself to others. If you do so, you are insulting yourself,” which is ties into the existentialist concept of authenticity. But it would take mental gymnastic to try to to equate this quote with the other stuff Hitler did and or believed. It would be absurd to associate the hackneyed expression ‘be yourself’ with Nazism.
Nietzsche’s dictum is to “become who you are,” which is similar to the US Army’s slogan “Be All You Can Be,” but what does that mean? To fulfill one’s own purpose/existence can be innocuous as working at a charity, to on the other extreme, becoming a spree killer in order to leave a ‘permanent bloodied mark on society’. 
Consequentialism and utilitarianism, but also Kant’s categorical imperative, when taken to their logical extremes can be used to justify murder. The first as a matter of outcomes justifying the means; the latter, ‘good intent’.
The question is, how much can the philosopher be blamed for the consequences of his beliefs? Marx, being that he was economist and political philosopher, and whose writings called for revolution, is perhaps closer to bearing responsibility than, say, Plato.
The Communists disdain to conceal their views and aims. They openly declare that their ends can be attained only by the forcible overthrow of all existing social conditions. Let the ruling classes tremble at a Communistic revolution. The proletarians have nothing to lose but their chains. They have a world to win.
Probably the most ‘benign’ philosopher is Hume, whose skepticism precludes any possibly of absolutes. Hume rejected the idea of using rationalism and science to solve ethical problems. A philosophy can be oppressive if adherents impose its values based on a self-proclaimed superiority.
Regarding the atrocities of Communism, the blame lies with Stalin, Pol Pot, Mao, Lenin etc., all of whom interpreted Marx as an invitation to despotism, just as Hitler and the Nazis interpreted Nietzsche to their own ends.
 Existentialism, related to individualist anarchism, although related to Marxism, reject fatalistic economic determinism.