It can write a chess engine because it has read the code of a thousand of chess engines. This benchmark measures a different aspect of intelligence.
And as a poker player, I can say that this game is much more challenging for computers than chess, writing a program that can play poker really well and efficiently is an unsolved problem.
The most popular form was solved in 2019: https://en.wikipedia.org/wiki/Pluribus_(poker_bot)
Pluribus didn't solve poker. It's limited to fixed starting stack sizes. It can't exploit weak opponents, it tries to approach a Nash equilibrium, but in multiplayer poker, Nash equilibrium doesn't have the theoretical guarantees it does in head's up. And lastly, it requires a ton of compute.
The program doesn't need to be a solver. It can be anything that helps it.
It doesn't even need to be one tool but a series of tools.