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
RTSes present continuous, large choice spaces. So it doesn't really feel like as much of a logic puzzle, and perfection does not appear to be within ones grasp at every moment. Whether you'll lose 4 or 6 of the T2 fighter-bombers is not relevant. The strategy of RTSes is strategy of big plans and high level abstraction.
That's not true in all RTSes. Take StarCraft, for example, and there are plenty of games on record that were decided not just by 1 unit, but by 1 attack from 1 unit. There are Zerg players, for example, who have developed a reputation for creating havoc after getting a single zergling (the smallest and cheapest attacking unit) into their opponent's base. A single shot from a Protoss reaver can mean the difference between taking minimal damage and losing half of your workers (and subsequently the game).
But I'm thinking about TA-style games, the topic of this discussion, which pride themselves on large armies. Though, to your point, early game of Supreme Commander is also quite chess-like, because of how restricted the set of opportunities is.
Chess surely has a meta, but it's been honed so the meta is a huge number of significantly different paths. It's a balancing issue. Give Starcraft another few centuries of play and maybe it'll be the same.
That said, I don’t know if it is true in those cases.