Maybe, but that's now how addictions are generally fixed. Even for simple physical ones, like caffeine, kicking the habit is a complicated process, and is best done with careful preparation and a nuanced understanding of how the addict benefits from the addiction.

That's even more true for more serious addictions. There are always reasons somebody became an addict, and preventing relapse often requires solving those problems first before any real headway is made.

Generally, the "just say no" advice is much more fun to say than it is useful to the addict.