I used to foster and my last 15 year old was 10 times the work than the 5 year old that preceded her.....
Sadly, the reason the 15 year old was like she was-— was because of rotten parents.
For kids, it just is not so. They like clear, clean boundaries, consistently enforced. They'll push them and test your resolve from time to time, but once they find out you will stand your ground, they feel more secure as a result.
They won't feel secure in a world without standards and rules, because then no one has rules to go by, just the whim of the moment.
But using no standard more stringent than the "if it feels good, do it" guideline, they are destroying their children in the guise of "being their friend". If they would be the parent now, the friendship will come later, and the kids would be better, happier, people for it.