You are so right that teenagers don't have the life experiences to cope with stuff but that we, as the adults often do. And that is why , although I will always love mychildren if they are being a horses arse over something, I'll tell them.
Because I'm the grown up.
Giving in all the time just makes you a doormat. Parenying isn't a popularity contest, I'm not there to be their 'mate', I'm more important than that, I'm their mum.
They know I love them, they also know I've got teir best intesests in mind.
My kids are not teenagers yet, but I run the same rules in my classes at school. I'm very fond of the kids I work with, but in the end just about all the time I do know best cos, hey, I'm the grown up. And if they hate me in the short term, I don't mind, as long as they get where they need to be at the end.