That this person is definitely not looking to get their views changed since they already have their pre-conceived excuses ready. Clearly even half-truths can be used to engage in anti-intellectualism.

Furthermore historical materialism is a theory of history, not a series of predictions. Marx could very well be wrong about a number of predictions, but that doesn’t negate the explanatory power of the method itself especially in contrast to other theories where history is little more than a string of accidents.