What if people don't share your priorities and would rather smoke despite the health consequences. Where does this line of thinking end? Why should someone else get to tell us how to prioritize pleasurable activities vs health and longevity.
The argument about misleading advertising I understand, and if you'd said "advertising portraying smoking as safe would actually be banned" then I think there's a clearer argument (despite my being uncomfortable with the idea of "misinformation" being targeted, we have lots of reasonable precedents for statement you can make about products you sell). But legislating what people's health priorities should be is authoritarian and not a power government should ever have.
Why should tobacco be banned? That's just another war on drugs that didn't work for alcohol or pot, and isn't working for the current illicit drugs. People should be allowed to smoke what they want, as long as it isn't a health issue for others. If young people in Spain want to smoke outside or in their homes, so what?
Despite being only able to smoke outdoors I still see many young people in Spain taking up the habit.