The controversy is between physical addiction and “psychological” addiction, a more-or-less bogus distinction:
“The distinction is completely arbitrary. Psychological addiction occurs in your brain and it’s a physical change,” says Dr. Nora Volkow, director of the National Institute on Drug Abuse. Different brain processes may be involved in the psychological drive to take drugs and in the physical withdrawal symptoms when the drug is stopped — but both are brain changes.
We have also to consider the fact that the amount of THC (the psychoactive ingredient in marijuana) has become much higher in illegal strains over the past twenty to thirty years, so much so that there is little useful comparison between the pot of the ’60’s and the current crop.