I agree with that statement but that doesn't mean that an older child shouldn't be able to enjoy a Phantom with a parent under close supervision. I would say that starting the child on the smaller drones first is a smart move (and my son started on the Micro Drone 3 - and can fly that pretty well too). One aspect you have to judge is skill and maturity - and to a certain extent decision making...... and much of that is built on experience which you only get with handling time. By the way, the same can be said of anybody flying light aircraft - you technically get enough skill to pass an FAA test at 40-50h legally but your decision making (and handling skills) improves with hours accumulated.
Interestingly, I also had my oldest handle the flight controls of my Cessna 182 when he was 8 or so. He could do level flight, and some basic un-cordinated turns (mainly due to the fact that his legs couldn't reach the rudder pedals

). All was safely done at altitude and with my complete supervision..... but it was a nice introduction.
John