Well this half true at best.
There is the additional addiction of the physical action just like addicts can get addicted to the act of using a needle, but this is in addition to the severely addicting nature of the substance itself.
Any drug that affects dopamine has the potential to be highly addictive. Nicotine is one such drug.
I guess your comment is case in point. People still don't understand psychological addiction. Yes, nicotine is addictive, but it's a small component of cigarette addiction. If it was just about that then patches would be 100% effective (in reality their success rate is dismal) and people who never smoked would use patches to get a "hit".
So I guess you could think of it the other way around. If you can believe scrolling is addictive then you should also be able to believe that putting a stick of burning plant matter in your mouth is addictive. Once you open your mind to the reality of psychological addiction you'll see it everywhere.