Imo, going from OpenAI Five to some kind of OpenAI FiveZero or whatever is like 1000x the amount of progress of AlphaGo to AlphaGo Zero, just based on the complexity of game mechanics and the fact that it's 5v5 and not 1v1.
and perfect vs imperfect information - the policy network has to forecast enemy positions and deduce enemy goals. At least in Go you know full game state