wealthy people have more choices than poor people. doesn't matter where the wealth came from.
In this case, if a family can afford to relocate to another state, just so a child can play a sport, they obviously have the means to do so. means that another family might not have.
to be fair, it all depends on the other state's residency requirements for athletic eligibility. for a student coming into MN, if they want to be eligible immediately, the family - or at least one parent - must relocate their primary residence into the new school district. you can't just send Junior to stay with Aunt Sadie for a year. Other states may not have the same requirements.
and - FWIW - there are ways around most rules. I know of a family that claimed the parents had separated. Dad and kid moved into another district - which just happened to have a much better basketball program. After kid used up his eligibility, Mom and Dad reconciled. everyone loves a happy ending.