Smoking, for all the bad things it does, it can have a positive effect of hurting parasites in your body. Maybe, to the average person, the benefits from smoking (killing of the parasites in your system) were greater on a net basis than the harms (getting cancer)? In this case they’d rather have most of the population have parasites thank have a small percentage die of smoking induced cancer.

That’s the only reason I can think that they’d target smoking so aggressively.