>>9451735while I think there is validity to this point, I don't think drugs "created" these songs. The human soul is a beautiful, expressive thing that drugs can enhance but actually putting the work in, creating and touring requires discipline and years of dedication. Most likely the junkies were carted around by handlers or family, and put into rehab long enough to pop out a few songs.
All the old masters before the 19th century had to literally work themselves up from apprentice with little more than snuff, opiates or (mostly) alcohol to distract them.