> It doesn't matter if you can in theory stop but not do it or if you cannot physically stop
It matters a lot, if you want to use the term "addiction".
Addiction has many definitions, but usually it involves a habit or compusion to some behaviour or consumption of some substance, often with and despite negative consequences (e.g. mental or physical health, employment issues, relationship issues), and often with negative consequences (e.g. withdrawal symptoms) upon cessation.
A single large beer every evening may be a habit, and your friends may miss that habit if they were to stop, but I'd suspect they don't experience significant negative life consequences from that single large beer, and nor would they experience symptoms of physical withdrawal if they stopped.
