It's the "lowest common denominator" approach. Many folks feel that since every 10 year old isn't mature enough to dive safely then no 10 year old should be allowed to dive. It's "flat earth" thinking but it's today's paradigm.
One of my favorite quotes from my youth was my Grandfather telling my Grandmother "Agnes, how're these boys ever gonna
learn anything if you don't let 'em
do anything?"
I reckon we had the best of times - my situation wasn't that unusual -
Hunting at six (with direct supervision)
Going fishing with my buds at 7 in "my" 3 horse skiff without direct supervision. (at 7 I knew how to change a shear pin)
Hunting on my own by 10.
Off-road driving at 12.
Private Pilot at 18.
Commercial ASMEL & Flight instructor at 19 (well, that one's a little unusual)
Rick