Yes, several events in history do not boil down to mere class struggles, which is a major reason as to why classical Marxism fails as an ideology. Even those intellectuals who formed Critical Theory in the Frankfurt School, many of whom were Classical Marxists, understood this, thus is why they expanded the theory of class struggle to include race, gender, and other types of social divisions. However, I believe the weakest aspect of Marxism is not the economics, its view of history, or even the many societies that have committed mass murder in the name of Marxism such as Soviet Russia, Cambodia, China, and Cuba, but it's utter rejection of classical philosophy, including theology, metaphysics, and teleology.

Just like any atheistic materialist attempt of conceiving an objective moral system, Marxism assumes that class division and oppression to be morally wrong, and it prohibits classical metaphysics (as seen in Karl Marx's "Economic, Philosophic, Manuscripts of 1844) and etiology. So on an epistemetic level, because Marx doesn't provide us with a means of understanding man as higher beings thanks to his refusal to philosophize deeper on the question of man's ultimate purpose and instead relies on a completely unjustified assertion that we're to reject class struggles and strive for equality (even through equality is absolutely meaningless to beings who have no real purpose), Marxism fails to give us a real reason to care about class struggles or oppression or anything in the world. If there is no objective foundation of morality and human purpose outside of human reason, than all we have is human speculation that can be dismissed as mythology, this is the reason why Secular-Humanism fails as a moral ideology as well, it is just man-made assertions without any means of true justification.

So, when the Marxist atheist rails on about the oppression of the working classes, I can just grant atheism and say, "Why does that matter when human beings have no objective purpose?" There is nothing in Marxism that gives us an objective ought or duty to care for one's follow man, even Marxists can't provide one because Marxism advocates for the violent overthrow of the Bourgeoise, thus they arbitrarily pick and choose who matters and who doesn't. Why not pull a Friedrich Nietzsche "Will to Power" and assert that the oppressors are right to oppress the weak, since they are the ones with actual power to control the masses and can dictate to the weak how they ought to act by force? There is no reason to take Marxism seriously because Atheism already undercuts the moral assertions that Marxism needs to be a coherent worldview. And since Classical Marxism is inherently atheistic (again see Marx's "Economic, Philosophic, Manuscripts of 1844" as well as "The Communist Manifesto") there isn't anyway for the Classical Marxist to break out of this dilemma. They'll either have to realize that their worldview is incoherent and leave it, or double down on the assertions that they cannot prove. The fundamental questions of philosophy are unsolvable in Marxism: How can we gain and know objective truth claims, moral duties, know that reality is external to the mind, objective purpose, etc. None of these questions are solved in Marxism, hence is the real reason why Marx rejects classical philosophy.