You can do many things to control blood sugar and to lower cholesterol not just cannabis so it’s not strictly some sort of panacea, but research shows it can help.

What confuses me about what you wrote is basically the idea that some kind of conspiracy exists to deny adolescents cannabis. There have been studies on the affects of cannabis on the adolescent brain for example This one from 2011 shows differences in brain tissue integrity following heavier marijuana use does predict future risky behaviors such as increased marijuana use and aggressive and delinquent behaviors many observational studies in humans imply a link between teen marijuana use and poor outcomes but are clouded by several potential confounding variables, such as socioeconomic circumstances or family mental health history. There does need to be more research but I doubt the conclusion will ever be “it’s so beneficial we recommend all children between 13-17 take it.” It’s always better to err on the side of caution and wait until their adults and brain has fully developed.