If you really want to fanwank it, there’s also the fact that to play the game, you had to become one of the pieces. It could easily have been that the controlling intellect wasn’t playing a perfect chess game to win - it was playing in a manner requiring the other side to sacrifice an actual person to win, as Ron did.
There’s a Kurt Vonnegut story where a southeast Asian warlord captures a downed plane, with a General & his family & the crew. He forces them to play human chess (giant chessboard & everything) against him, with the general as the king and everyone else, including his family members, as other pieces. Whenever one of the human pieces is lost, he shoots the victim.
In the end, after he’s lost a few crewmembers, the general realizes that to win, he’s got to sacrifice one of his young sons - the warlord’s bloodthirst will (and does) lead him into a trap.
The points tally only mattered in the 3rd book, because the teams were level on wins. After Gryffindor beat Slytherin, the match standings were Hufflepuff 1-2, Ravenclaw 1-2, Slytherin 2-1, Gryffindor 2-1. Hence the importance of the total points!
Oh yeah, now I remember Wood trying to work out the combination of wins & losses needed.
In that case I’m going to join the legions of the “Makes no sense” crowd, with a smattering of “Games used to last much longer”. Everybody gets excited and/or worried about the prospect of matches lasting for hours, days and weeks, but we never see one. I guess it would be a challenge to keep the World Cup interesting in a narrative sense over several days, but it could have been a background to the action rather than the key focus.
That’s assuming Rowling meant us to think that much about it, which I doubt - knowing that games could last for ages is enough.