Currently
I'm doing a LetsPlay of the Hard Campaign of AdvanceWars 2. One thing I've noticed so far is that there are several missions where I would not have won if it wasn't for ArtificialStupidity. A human player in the AI's position would have, if not outright crushed me, at least done things that would have cost me the mission (like damaging a crucial capturing infantry on a timed lab mission). But because of flaws in the AI, it isn't "sane" enough to spot these things and I've been able to pull through. So even though the AI always seem to outgun you, you biggest advantage is that you're sane - or at least, sane enough for AW. I imagine it's the same for any game where you're competing against an AI.