Okay, I can’t find the exact passage I was thinking of (maybe I invented it), but there are a couple good spots to check out. I recommend reading chapter 11; see also this passage on page 15 (kindle edition):

…but today there is a rising recognition that all mental disorders exist on a spectrum, with no clear transition in the data that tells us where to draw the line between mild and severe issues. This is why the… DSM… has done away with the division between “substance abuse” and “substance dependence,” the latter of which was a stand in for addiction. “Spectrum” concepts have been gaining momentum… and the neurodiversity movement seems to challenge the notion that mental disorders are inherently pathological…
People use drugs for reasons; the banality of that statement is matched only by our constant lack of mindfulness to it. The message screams from the pages of addiction memoirs. Caroline Knapp describes how “liquor occupied the role of lovet or constant companion,” crating an illusion of emotional authenticity that seemed like it granted access to more meaningful feelings…
…
p 18:
…for example, there is a strand in addiction advocacy today that seems to replace “person with addiction” with “person with substance use disorder,” seeking a more compassionate and less stigmatized term. However, the terms are not really equivalent: “substance use disorder” included a huge swath of people who have substance problems but do not necessarily feel like they are struggling with internal conflict or self identify as addicted… (p.19) Harry Frankfurt distinguished between “willing” and “unwilling” addicts–both have an immediate desire to take a drug, but the willing is not conflicted about it, and the unwilling doesn’t want to have that desire…