I think, and God knows if "they" don't know I'm don't, addiction is a disease of the brain. It is a brain disorder that manifests itself in different forms.
We know that a chemical dependency occurs because the detox can be so dangerous. We also know from scans that the alcoholic brains look different than drug addicted brains from food addicted brains. Different forms of a brain disorder.
I don't know if each addiction is a separate disease. I don't know that anyone does . . .
And really does it matter? If drinking alcohol is a symptom of the disease of addiction or the disease itself - the outcome is the same.
*AND let me clarify - 'matter' to this board. Not the world of science.