(In practice, except possibly for heads-up limit hold'em, good players are still better than the best bots published in the academic literature anyway.)

This is an interesting observation, but probably not that surprising: if you had a superior poker bot that was consistently profitable, why on earth would you publish it?

Generalizing, if someone working at a bank or hedge fund developed a superior theory of economics, and that theory could be used to make money through trading, why would they tell anyone else about it? Once the knowledge became public, it would no longer be profitable.