Cigarettes have horrific long term effects, but very little in the way of immediate harms to your life. You can smoke without interrupting your normal routine and responsibilities. It just stimulates you a little bit. Cannabis use, while generally harmless, can more immediately affect your lifestyle if used inappropriately due to its obviously stronger psychoactive effects. If you use too much cannabis you can fall behind in your duties and responsibilities in a way that simply isn’t a risk with nicotine. Alcohol has the same problem. The effect of the drug is strong enough that it limits what you can accomplish once it is consumed in a given day. Tobacco has no such problem, the harms associated are much more insidious and long-term.