There are posters like this in many local shoe shops. You might have seen advice like it before.
The human foot has 26 bones and 33 joints. The joints are meant to move. The muscles are meant to contract and relax. With each step the ligaments and tendons that attach to the bones of the foot provide shock absorption, like a spring. There are thousands of nerve endings providing ongoing sensory feedback to the brain to help the human move skilfully.
Telling parents to lock up their kids’ feet in the stiffest shoes available is like advising them to hobble their kids with a plank between their ankles.