Think for a second, though. Let's say you're on a team that was created for the sole purpose of maxing out a scoresheet - 1000% tumbling, everyone has doubles, ridIculous stuff. A cheerleader blocks a month before Worlds. Everyone works with the athlete to get the skills back, but she just can't. Meanwhile, Betty Beast on a lower team has all the skills the blocker had and knows the routine. I would expect the coaches to pull Betty up and move the blocker down.
Just like any other rule, the gym had sense enough to put it in writing that scenarios can happen, not that they WILL pull (see @
Fameous MOM 's example) but that they CAN if necessary. Plus it eliminates Susie or her Mom running and crying about being leveled down.