When I was 11 years old, I spent a day in Disneyland by myself while the folks were at a conference nearby.
I didn't break anything. I didn't cut in any lines. I bought my own food. I didn't get kidnapped. I did ride the Peoplemover a lot.
How did I possibly survive?
Also, doesn't this create a possible danger with kids who get dropped off by parents without knowing about this new rule who then seek adult strangers for admission rather than calling their parents on the phone to come back?