In poker even the thing you're celebrating is zero-sum. Could person A fool person B or could person B read them; that's not people collaborating to create something in the way that two tennis players beating out a long rally are, that's just A vs B. And so much of the game is simply random luck - does the right card fall or not - and that's what people want to see; you might say there's skill in the game and that might be true, but people don't watch poker for the chess moments where someone makes a brilliant move, they watch it for the moments when the right number comes out of the random box. The larger luck factor matters.
