I think that can be chalked up to other changes like the wild increases in cigarette prices, the near elimination of advertising, and cigarettes becoming culturally uncool (orthogonal to DAREs attempts). Your link shows that during the heyday of these campaigns usage rates were still rising. They didn't really drop until after the approach was dialed back, and they dropped most appreciably after DARE gave up on anti-drug messages entirely.

The message of the article wasn't that you can't discourage drug use at all, it's that the means may be counterproductive. The means used in DARE were counterproductive.