I'm not disputing that. But someone doesn't simply decide to acquire that much of a very serious drug with a sound mind. Is it fair to treat a crime the same for two people if one person is suffering from schizophrenia and the other is of sound mind?

Simply saying "you did a terrible thing, and that's irredeemable" isn't useful to society. What good are you doing if you've rehabilitated the criminal? You're just spending tax dollars on principle. It's cruel and unproductive.