Who is responsible for smoking remains the same.
The cigarette manufacturers? The retailers? The smokers themselves? Ad agencies? Nicotine? Workplace anxiety? Who IS responsible?
The kind of responsibility being discussed when someone neglects their duties is different from what is being discussed when we are talking about de facto responsibility.
It is not, because its not objectively certain where the buck stops.
A group of people is de facto responsible for a result if it is a purposeful result of their joint intentional actions.
A group of people can engage in individually virtuous actions while generating a villainous result. The classic example is the "Tragedy of the Commons". Six individual shepherds grazing on a hill that can only support five flocks. Each doing an honest day's work, but collectively destroying each others' livelihoods.
Individuals lack perfect information and cannot be held culpable for unforeseen consequences.