While it is a contributing factor, physical dependence- withdrawal is not anymore considered necessary or sufficient for addiction. The author there is using an outdated pre-DSM5 definition of addiction which failed to recognize that there are two separate but related phenomena here. Things like gambling and sex addiction obviously cause no withdrawal symptoms from chemical dependence at all, but can be almost impossible to quit and serious enough to destroy someone’s life.

Severity of withdrawal symptoms from caffeine also varies substantially from person to person. It’s probably not directly killing anyone, but for some people it can be brutally unpleasant and disabling for at least several days.