Well, my take on this is that, at a certain point, addictive behaviour stops being a symptom of something else and becomes a disorder in itself. Meaning that treating the underlaying causes will not necessarily clear up the addiction. I think that the only way to know you've crossed the line is by realizing that you already have a problem. Unfortunately, most people don't stop until it's too late. The good news is, if all goes well, most people DON'T want to go back anyway.
It's a matter of semantics, mostly. Labels, disorders, etc. BTW, I know that my point of view differs from the official medical stance, and AA's too. But that's what works for me. You'll probably get lots of different answers.