> Two humans playing each other, it's just a question: who's score goes down less each time they make a move? It became a little sad. It seemed like either you can make the right move, or you make a sub-optimal move, and the winner is simply the one who makes the fewer sub-optimal moves.

What you describe is when a perfect chess-playing computer (approx AlphaZero) observes two humans playing. What humans observe watching two humans playing (including the participating humans) is very similar to what you described AlphaZero vs Stockfish as. The only difference is we don't ask human players to ascribe a score to their opponent's move (and wouldn't expect it to be accurate)