Argue that it's empirically false, even, and see how the pushback you'll receive isn't at the level of empirics but at the level of philosophy of science. Then empirics has nothing to say til we decide what proof looks like. Philosophers can pre-empt this by staking their claims in that realm, where rationality is our only tool. The Real is Rational and the Rational is Real, as Hegel liked to say

I'm not sure why this obsession with just one part of what I said when I brought up empirical studies. Not only did I never claim that philosophers generally try to produce research backed by empirical testing - I am fully aware, that their studies are usually attempted as rational, - I also brought up rational studies, i.e. ones backed by logic. Hell, what sort of studies do you think mathematicians produce - empirical or rational?

If a work of research is not backed by logic, and is not backed by empirical studies, why should it be listened to over any two random people having a casual conversation about whatever it is they want to talk about in the kitchen?

And a small point: if you think philosophy isn't needed to be a good Marxist, you're in disagreement with every famous good Marxist I know of. Lenin fuckin loved Hegel and hated his idealism simultaneously

I am both fine disagreeing with people, even if I hold them in high regard, and also fine with them not understanding what idealism is.

And yes, as a mathematical Platonist, I am an idealist. And no, I do not see that producing any sort of significant disagreement with any sort of Marxist thought. And yes, people have tried directing me to the writings of Marxist thinkers who, supposedly do claim that there are such disagreements, but what they seem to address are Renaissance-inspired idealist schools of thought. Even then, they fail to address all of such schools of thought, as, for example, by their definition(s) (they seem to all concur on one), various types of Christian idealism are not idealist schools of thought.