I'm guessing the same reason you don't argue balls and strikes in baseball. It's tradition. There is a rough system to it and people are used to they way it works. Pre-1990ish, they wouldn't even alert teams how much extra time they were getting. They just kept playing until the whistle sounded whether it was 1 minute or 5 mins. stopwatches have been around for a long time. magic lasers that can call balls and strikes have been around for like ten years.