Because there was no pot smoking in the 60's or 70's. Those dang ultra conservative baby boomers! The reason you can smoke dope today without the cops kicking down you door is because of the Baby Boomers. Y'all ain't that special, you are just spoiled.
I get it. You like to smoke dope. I don't care, but equating child molestation and smoking dope is not a reach if both are crimes. You don;t get to choose which laws you obey. More than an ounce is a felony in Miss., and since the picture appears to be a dorm room, I believe it was taken at Ole' Miss.
Aside from that, smoking dope lowers your IQ and does brain damage. Not a myth, a fact. Some folks don't read about that because you don't want to hear the negatives.
NAMBLA would argue that love is love, and the laws prevent it are oppressive.