A group stops working when somebody outgrows it. Strength is not age, so a nine-year-old may belong with teenagers, and tracking who has moved beyond their class is what prevents both boredom and discouragement.
The rating is the renewal argument. A parent deciding whether to continue in September responds to a number that rose, so recording each student's progress across the year is a commercial record as much as an educational one.
Entries have hard deadlines. Tournaments close registration weeks ahead and charge fees per player, and an academy that misses one has disappointed a family for an administrative reason.
The timetable is scattered. Coaches teach at schools, at a club and online across a week, so knowing who is where, and which students that leaves unattended, matters more here than in a single-site school.