It's a disease so it's ok is a strange, strange argument. The point of acknowledging that it's a disease is to get help and to reassure the addict and those in his/her life that it's not a lack of morals or that they're necessarily a bad person that's brought them to this place. It's not a permission slip to indulge in their vice.

Think of it like OCD, a disease causes the obsessions and compulsions that interfere with the person's life but the goal is to be rid of said obsessions and compulsions, not to embrace them.

Cyran0