In most cases, people gain expertise through direct experience. This is not true when it comes to addiction, where legitimate expertise is derived from a lack of direct experience. There are many reasons for this, including cultural investment in educational prestige, faith in systems of authority, resentment of those who take their pleasure in what Derrida calls “an experience without truth,” and a distrust of addicts, who are “by class the most lying, scheming, dishonest group of patients.”
So when it comes to talking about addiction with any sort of legitimate authority, we generally turn to those with letters after their name rather than those with addiction in their background. The field of expertise has changed over time, from moral to legal to medical but, with very few exceptions, addicts have not been included in the cohort of experts.