You're still thinking one hand at a time. It may be possible to confuse the opponent into permanently shifting strategy.

I agree that would not happen if two equilibrium-seeking computers played each other. Since the human strategy is unknown, it is possible that equilibrium may not exist or be optimal. Even if it's two computers, if one of the computers has the possibility of choosing a non-equilibrium strategy, then again the optimal strategy may not be to seek equilibrium.