I recommend posting this to the philosophy community rather than politics. I think it might help to remember that what people mean by materialism has changed overtime, and that most are just physicalists, believing that all reality is physical. In doing so you don't really need to posit a fundamental substance such as matter, nor must you ascribe certain immutable properties to it such as the inability for another object to occupy the same space (bosons can occupy the same space), or extension (existence of point particles), which older materialist philosophy prescribed to. As our natural sciences develop with the development of new technologies it would make sense to change our notions of the intrinsic nature of reality with them, rather than just accepting an older materialist metaphysics that just seems correct. Marx and Engels saw the need to bring the older 18th materialism up-to-date with the new revolutionary scientific advances of their day, most importantly evolutionary theory, which is why they saw great value in Hegel's interconnected, processive, and developmental philosophy. As such while Marx and Engels never used the term, "dialectical materialism", they essentially sought to synthesize the developments Hegel's dialectics had made in the sphere of philosophy, but to ground them with the new developments of the material sciences.
I recommend posting this to the philosophy community rather than politics. I think it might help to remember that what people mean by materialism has changed overtime, and that most are just physicalists, believing that all reality is physical. In doing so you don't really need to posit a fundamental substance such as matter, nor must you ascribe certain immutable properties to it such as the inability for another object to occupy the same space (bosons can occupy the same space), or extension (existence of point particles), which older materialist philosophy prescribed to. As our natural sciences develop with the development of new technologies it would make sense to change our notions of the intrinsic nature of reality with them, rather than just accepting an older materialist metaphysics that just seems correct. Marx and Engels saw the need to bring the older 18th materialism up-to-date with the new revolutionary scientific advances of their day, most importantly evolutionary theory, which is why they saw great value in Hegel's interconnected, processive, and developmental philosophy. As such while Marx and Engels never used the term, "dialectical materialism", they essentially sought to synthesize the developments Hegel's dialectics had made in the sphere of philosophy, but to ground them with the new developments of the material sciences.