The issue is why people feel compelled to self-medicate. A beer or glass of wine or a dram of whiskey can be food and/or something to be enjoyed. Or it can be abused as a drug. Anything in excess, whether it be food, alcohol, weed, shopping, sex, exercise, etc, especially if it's being used to check out of the reality of one's life, is dangerous. Granted, pounding a bottle of Jack and running 10K may have opposite effects on the body, but if you're checking out, then you aren't dealing with the organic neurological and/or dysfunctional emotional issues.
Whether weed is more benign than alcohol hardly matters if your inclination is to wake and bake, slack at work, let the kids cook dinner for themselves while you sleep off a bong-hit or any of the myriad other chronic stoner check-outs.
I say treat emotional/mental illnesses as we would high blood pressure or any other disease. I bet if the stigma for treating behavioral health issues were removed, we'd see less in the way of substance abuse, and lifestyle diseases such as Type II Diabetes and obesity would start dropping in reported cases, because then we'd finally admit that the brain is the most important organ in the body, and its health governs much of the overall health of the body. We'd also notice a drop in child abuse, spousal abuse, personality disorders, and see a lot higher quality of life.