Starcraft might be more complex in absolute terms (not sure about that - discrete combinatorial problems can be genuinely more complex can continuous ones, from an algorithm point of view, because solutions are harder to come by)

But chess theory, the human activity of analyzing chess, is hugely more complex than whatever human players have analyzed about the game of starcraft

What I mean is, perhaps the best neural networks that play starcraft are as complex as chess neural networks, and this complexity is irreducible, but starcraft players haven't developed as much theory in comparison