as how I see it...
by being addicts, there is a hole in our soles, created by our own efforts to destroy ourselves. (there are also scientific ways to look at this, adrenaline, endorfine etc. but i prefer this one). filling this hole up with another drug doesn't close it. You keep your open wound, only you change the type of bandage. You still look for something that just is not there.
By being in recovery, wether you use the steps or another programme of some kind, the wound actually heals over time...