I think the addictive vs. non-addictive debate is mostly about what people mean by the word "addictive." Clinically, you're right: anything that affects the dopamine system will have clinically addictive properties (i.e. bingeing, preoccupation, anxiety, etc), and there's plenty of clinical research showing that long-term cannabis use can result in addiction. But what people sometimes mean by "addictive" is physically-painful and/or physically-dangerous withdrawal symptoms: nauseau, migraines, shaking, or even potentially death in the case of alcohol. Even heavy cannabis use doesn't generally result in those kinds of withdrawal symptoms.