It's not true that products unsafe for smoking are not marked - they are; moreover, there's both infrastructure in place to increase safety (e.g. physicians and filters) and a significant amount of effort put towards educating people about the dangers of things like using tobacco in a potentially unsafe manner.
I believe that time and history has proven that prohibition solves little, where infrastructure to increase safety and effort put towards educating people results in "less harm" -- a much better outcome for all. Some people will make a harmful choice (e.g. heavy smoking, fast food diet, sedentary lifestyle, using chainsaws alone), but society as a whole should not be punished for the choices of the few.