It's not just the limited information space, however. There's also the solution space or "action space". A poker game-space is quite narrow compared to that of StarCraft because of pixel-wise differences. This is the main reason that makes StarCraft "much more realistic". In real life you have infinite moves and options with (almost) analog differences, whereas a game like Poker is much more discrete. Go is somewhere in between.

For instance, as any protoss player knows this all too well, a Zealot placed a mere pixel away from where it should could allow a stream of zerglings in, completely throwing any game plan you had up to that point out the window and enter crisis management mode. Usually this is a "mistake", which a computer may never make, but it needs to learn the relevance of such pixel-sized mistakes, which is unlikely to have as much of an impact in a poker game or Go game as it would in StarCraft.