"Today's kids are raised like veal." -Lenore Skenazy and Jonathan Haidt
This is due to many reasons including
...a heightened fear of abduction (missing kids on milk cartons made it feel as if this exceedingly rare crime was rampant)—children largely lost the experience of having large swaths of unsupervised time to play, explore, and resolve conflicts on their own.
Let me add that you cannot enter a grocery store around here without having to walk past a wall of America's Number One wanted children. Close reading shows they are from across America.
They are horrified when an adult strikes up conversation. They believe the stranger will pull out a gun and start shooting.
Consequently it is necessary to engage them in safe activities like gymnastics.