The problem with stuff like that is that you'll still have the law enforced, just in a haphazard way. So everybody is doing it, and most aren't any worse off for it, but some end up with their lives ruined, largely at random.
It does mean that maybe throwing people in prison for possession is not the brightest idea given how likely it is to be just some random guy who really didn't do anything that everybody else wasn't doing.
