Actually, if you want to trust what is taught in College level psychology there is some truth to that. It has been tested/shown that marijuana consumption can affect the development of the brain. Now, I don't say I believe in this. Nor, do I oppose it. I honestly don't know if it is true or not. Why can't I simply trust scientific evidence right out of the box? Because it has been shown very often that objectivity is skewed. Often results can mirror what a scientists might choose as evidence in the conclusion. As an example. If the scientist is anti-MJ. His results may be skewed by evidence that supports his position and leave out some opposing evidence.
My friend of 25 years were talking the other day. More so about alcohol and we were discussing how over the last 35 years for me. 30 plus years for him. How our bodies react anymore. He is still an everyday high consumption drinker. I drink mostly weekends these days. But, 6 years ago I drank a liter a day and rarely, if ever didn't drink straight whiskey. I told him, sometimes I feel the need to drink anymore, just because I feel all those years, living that lifestyle and drinking that much alcohol has changed the chemistry in my brain. Sometimes I just need to get drunk during the week. Then we talked about the shakes. He was like, didn't understand what I meant by how I used to explain how I had the shakes(tremors) all the time. Because he hasn't progressed to this. Now he has. And I told him, even when you do like I do and only drink weekends most of the time. You will still have the shakes anymore. Because, I also feel the obsessive use of alcohol has permanently affected our nervous systems.
End of the day. Been drinking since like 12. Consistently since 16. Smoking weed isn't as consistent, nevertheless it is habitual to some. Me. Medicinal is a different matter. As for teens. I always encourage them to handle their business before they pick up these bad habits. Get your degree..... Etc.... Then party down if that's what you wanna do. Kids are different. To many things going on in with chemical changes. Some will be lost anyway. Some will be fine and walk away from it someday. So.....
In conclusion. lol. There really is none. They SHOULD WAIT. But, they will choose. And meet their own consequences, maybe, if any.
You were kinda on point.