Because we live in a society (that mostly) allows adults to make choices for themselves. Just because a few adults can't handle themselves doesn't mean that all

Because we live in a society (that mostly) allows adults to make choices for themselves. Just because a few adults can't handle themselves doesn't mean that all adults should be punished for it. You can say the same thing about gambling, smoking, drinking, eating sweets etc. Also, the effects on undeveloped brains are far greater. Our job is to teach kids and raise them. Not be their friends and just let them do whatever adults do.