It's a curious idea, this one that says that 'society' has a duty to protect people from themselves, especially when coming from people who are left wing.* By society, everybody clearly means the government (the idea of 'society' policing itself being a romantic dream.) In reality, governments only have a duty to present people with the facts when it comes to personal health. Personal behaviour being largely out of the control of anybody else, if people fall ill due to their own stupidity/liking for harmful substances, then they should be treated like anybody else and their treatment paid for through taxation like anybody else's. But, of course, we've already gone beyond that, with governments claiming that while they can't control capital, they can at least try to intervene in everybody's personal behaviour.
*I've even heard people say that society/goverment has a duty to help people live long and happy lives, as if happiness can even be defined, and as if a long life is a naturally desirable aim for everybody no matter what the circumstances.