In fact, Marx frequently argues that humans materialize their ideals. Marx's position straddles idealism and materialism, with emphasis given to the objective behavior relations, hence a realist position, and a favoring of material premises. Marx's sharpest polemics were against materialists, e.g., Feuerbach. And here is where I find Weber to be most in error. As Mead points out, individual action is only meaningful in its relations, and thus the social group is the appropriate unit of analysis.
Society is an objective entity.
Weber erred in denying this. As Mead points out, taking the social group as the analytical unit does not banish meaning and culture, since both meaning and culture are social products not the products of individual organism. The flaw in beginning with the individual for ideas is that it doesn't recognize where ideas come from, namely, the social group. This can apply to everything. Studies of physics can be said to be subjective in this regard because of the investigator's notions of what is physically significant.