> not least because if humans realise they're at a disadvantage it would be essentially impossible to prevent them from colluding with other humans to get an advantage, even to some extent unconsciously
Indeed versus a single opponent, you can play an "optimal" (e.g. Nash equilibrium strategy) and basically win/solve the game. But in a multiplayer setting (in poker and similar games), you rely on your ability to predict opponents. In the former you could essentially assume your opponent is as smart as possible ('rational' in game theory language), and if it is not rational it will necessarily do worse. In the latter however, by assuming every player is rational (e.g. playing N.E. strategies) you lack the ability to exploit weak players which are decidedly suboptimal, predict their moves, and capitalize. Thus winning is conditioned as much as the knowledge of your opponents, their skill and style, as in your own power to play probabilistic 'optimal' moves.
A good simple example is also Rock-Paper-Scissors: a N.E. strategy just plays randomly -- it clearly cannot lose even against the most skilled players every -- but it also cannot win versus weak, predictable opponents. So e.g. in a tournament setting it would always lose, depending on the tournament structure (in particular if tournament stages are not all pairwise elimination).
I find it a fascinating contrast to traditional game theory, and sort of conventional view of games, that there are "good players" and "bad players" in the sense of their execution being superior in an absolute sense, independent of opponent. In reality success in a variety of games (and real world scenarios) is won by tailoring your strategy to a particular opponent, using information from outside the game, and specifically predicting his plays vs. utilizing universal strategies (again this is particularly relevant in non-pairwise tournaments, non-zero sum games, etc).
In real life, almost always the "game" is non-zero sum, multiplayer, with non-rational players, etc., even in a sports setting. Roger Federer might play slack and save his body in the early stages of a tournament vs a known weaker player, and give it all vs his most fearsome opponents.
And also finally to quote "The Art of Strategy" (introductory game theory classic), 'There's always a bigger game.' (in real life it's the ultimately the entire Universe, and no one is quite sure of the Rules :p )