I'm not leading an idyllic life. Are you?
It's not about "idyllic", it's about relative levels of psychological damage.
And you can "like to see" sex delayed until 40, for all most teens care. They may not be making mature decisions, but they're still making them.
Idyllic? No. Pretty good? Yes. Far better than my life would likely have been like 1000 years ago. Very good chance I wouldn't have even lived this long.
Would you prefer to be living back when it was common for girls to be having kids by the time they were 14? How many sane women would want that?
My son has had "girlfriends" fairly regularly since he was 14. One of them from last year had to change schools when she was 12 or 13 because she had a "reputation" at her previous school as a result of various rumors. Some kid ended up groping her. This made her quite skittish around boys. Though you wouldn't expect any relationship among 15 year olds to last very long, the one she had with my son ended partially because of that. She's struggling. He goes to a small school. We know her parents.
I've seen many of his texts and unfortunately some of the pictures that have gotten exchanged between he and his friends. For the most part I consider it normal and harmless but it can very easily go too far and cause some real difficulties. He lost his phone for quite awhile because he made some bad decisions and we discovered them before it got worse.
So yes, they make decisions, and yes they should be allowed to make mistakes, - but there are times when parents need to step in.