• funnily enough, I think 'substitutes' here is as broad as smartphones. One of the major uses of tobacco products has always seemed to be as something to do with your hands, kill time, and idly socialize with others (as suggested by smoking studies where nicotine-free cigarettes offer relief, indicating that tobacco addiction is as much about the habit and activity as the actual chemical contents), and smartphones can do all 3 at once.

Never thought of that! How clever.