There's a great deal to be said for such an assumption. At worst, it turns out that one can't explain something in which case one is at least in the position to assert reasons for why this is so, and at best one is able to explain "everything". The one problem (as we've seen more from historical analyses of the sciences from those like Conant and particularly Kuhn) is that the more one's formulation of epistemic justification is made rigorous, the more one may find that the foundations are swept under one's feet (as in the case of Hilbert and some of the main goals of logical positivism or in physics). Marxist materialism rightly criticized the epistemology Hegel propounded (as this formalist approach was to come to a rather crashing halt thanks to Turing and Gödel while philosophers of science and logicians such as Quine, Putnam, Popper, etc.) tried to rebuilt a structure for empirical inquiry that did not depend upon the hopes that all of arithmetic (and by extension mathematics) could be axiomized and with it the then-queen of sciences become itself the logic of science. However, Marx's denial of formalism had its price too. He took for granted a notion so alien to human culture that it arose only once: the belief that a systematic investigation into the nature of the cosmos was both possible and desirable and could be (and should be) conducted within the appropriate framework. Before early modern "science" developed in Europe, the closest to science that humans ever came was probably among the Greeks, where the formal framework/logic was worked out there as nowhere else. However, it wasn't applied to the systematic study of natural phenomena.
The problem is that explanations of natural phenomena come to us naturally. We are predisposed to see cause where none exists and patterns where none are. It is primarily the formalism that Hegel (among others) espoused which allows empiricism to exist as a successful program. Yet Marx and Engels could no more realize this, given their historical contexts, than Hegel could anticipate the fall of logical positivism.
Nor could any foresee a different formalism now used as a basis for epistemic justification that is entirely compatible with the empiricism of Marx et al: game theory, Bayesian inference/reasoning (or subjective probability), non-classical logics, etc.
You know more about this subject than I do as I have only really been piecing together bits based off Wikipedia (with some really useful Marxists texts). I am familiar with Popper and Kuhn basic ideas, especially Popper's criticism of Marxism. Kuhn's ideas could almost have been Marxist in terms of 'paradigm shifts' or 'qualitative leaps' in human knowledge. It very welcome to see someone knows about Marx and is even complimentary about him and Engels.
Marxism is peculiar in the way it combines philosophy and science into an "ideology". Neither Marx nor Engels themselves were directly responsible for turning Marxism into a "worldview" which claimed scientific status, but Engels did imply this by approaching contemporary scientific theories in "dialectics of nature". This was something that happened (I think) as a result of Plekhanv (the 'father of Russian Marxism') and who knew and influenced Lenin. It was this that eventually led to the politicization of science in the USSR and the mistake of lysenkoism (which was chosen for purely political reason because it fitted the ideological preconception of Marxism better in the "class struggle" of ideas).
Making the ideas fit into this philosophical system comes at a high price from a conventional standpoint since in the 'small print' of Marxist philosophy, Marxism remains an 'ideology' and therefore claims to be in a state perpetual change with a heavy amount of relativism and uncertainty over the nature of truth- which is a considerable "loophole" if I'm being honest and dodges some major questions over it's reliability for predicting social development (as Popper rightly pointed out).