Saying something like "no social media until 25" would immediately have people discount Haidt's rational policy solutions as something not practically achievable, never mind probably not legal either.
https://en.wikipedia.org/wiki/Human_brain_development_timeli...
> There is no actual evidence suggesting that impulse control only finishes developing in humans in the twenties. It is a common misconception in popular psychology that the brain only fully develops by 25.[13] This may stem from a misinterpretation or oversimplification of studies which determined that development of the prefrontal cortex continues into the mid-twenties
>Human brain maturation continues to around 20[10] to 25[11] and even up to 30[12] years of age and beyond.
https://slate.com/technology/2022/11/brain-development-25-ye...