It can make sense if you flesh it out. The headline and two lines the musician said about it are shallow, but there's a grain of truth in there.
I do believe that overuse of marijuana is going to be a negative. Kids under 24 using marijuana is going to be a negative. And both of those are going to increase with legalization.
Neither are as harmful as prohibition, but they're still harmful.
Potheads don't need to be on quite the same level as alcoholism, but it should be closer than it is. If you're not acknowledging the harm of using the legal system to enforce this, his quote makes sense. He may not have stated it well.