The main argument is that OP is comparing apples and oranges.
Society is not suitable anymore to many of the things she objects to.
Schools won't let children walk home by themselves until they are y5 at least. Even then, with ever extended catchments some kids have long journeys on foot/bike by themselves without classmates to join them.
Some kids can't play outside because there's no one to play outside with.
Certain freedoms that might've been normal means some well intended person calling the police or SS on you. There is no village, there is no strength in numbers.
There's more awareness of the various dangers of too much freedom and neglect, even benign neglect.
Then there's school and All the added traumas and stressors like chaotic home lives,abuse,neglect, living with an addict etc . Years ago that would've meant kids dropping out, leaving home, or just not bothering and being excluded anyways. Today they have to carry all that baggage and go to school and behave the right way and learn in the right way.
OP seems to propose a sink or swim approach. She's obviously a swimmer , what about all the kids from her generation that have sunk?