Quidditch Makes No Sense and That's the Point
The problem
Quidditch has a fundamental design flaw that every fan notices eventually: the Snitch is worth 150 points, and catching it ends the game. In most matches, this makes everything the other players do irrelevant. The Chasers, Beaters and Keeper are playing a completely different game from the Seeker, and the Seeker's game is the one that matters.
The books acknowledge this. In the Quidditch World Cup final, Krum catches the Snitch even though it means Bulgaria loses, because the deficit was already too large. This shows that the Snitch isn't an automatic win, but it also highlights how rarely the rest of the game can overcome a 150-point swing.
Why it works anyway
Quidditch isn't meant to be a realistic sport. It's a narrative device. Every match in the books creates tension because the Snitch could end things at any moment, which means every match has a built-in ticking clock.
The sport also serves as a vehicle for character development. Harry's talent as a Seeker is his first source of self-worth outside of being the Boy Who Lived. Ron's struggles as Keeper mirror his insecurities. The Weasley twins' roles as Beaters reflect their chaotic energy.
And the matches are exciting to read, which is ultimately what matters. The sport doesn't need to make sense by real-world standards. It needs to make sense as a story, and it does.