We have laws to prevent somebody from jumping off a building to end their life when it crashes down around them. We have laws to stop them from abusing drugs that insure they get to rehab. We have laws that take vulnerable children away from parents who are unable to protect them. 

My family has known a young lady for many years that became sexually active at 12 in an abusive relationship and very quickly drifted to bad friends an substance abuse. Her parents have the authority to do what needs done and if they don't the state steps in. 

The fly in your ointment, is that when that vulnerable kid reaches 18 you say let it rip, let's take off all the protections and let them self destruct as if honoring their bad choices is the most loving way to deal with them. "Not all the girls were on drugs" you said. Stepping back and watching self destructive young women ruin lives all around them (including their own) isn't a rights issue, its a humanity issue.