"You're joining outside for a smoke?" The look of utter disgust on the faces of many non-smokers when hearing this sentence is often very telling. Unimpressed by the change in social norms which made it so that people actually go outside to smoke in the first place, which wouldn't have happened 50 years ago, numerous non-smokers have become intolerant.
That isn't to say that smoking is good for you, it clearly isn't. However, decades of anti-tobacco advertisement has emboldened people in the stance that smoking is a serious illness which needs to be met with the greatest deal of vitriol. While decades ago we couldn't even imagine Sean Connery as James Bond without a cigarette in his hand, playing his role as the masterful spy agent sitting in a casino while smoking a cigarette, today we spew fire at the mere notion of someone lighting a smoke.
We have made the repression against smoking not only into a measure of public policy, but into a societal disdain which goes way beyond the boundaries of civil discourse. Just ask yourself this question: which group do we treat similarly as we do smokers? In order to pursue their habit, we send them outside of bars, restaurants and clubs. We, amongst other horrible images, display smokers as bad as people who willingly mistreat their children:
You don't have to like someone's personal habits to be tolerant of them. A personal experience of mine illustrates this further: my own grandmother, lifelong non-smoker, would always isolate the terrace space from the rest of the house when smokers would be over, so that they wouldn't have to stand outside. It wasn't that she liked smoking, she even found it terrible, but she considered it an act of courtesy. She allowed smokers to have a place to smoke the same way we today cook vegetarian food when someone doesn't eat meat.
There is no reason to be a jerk to smokers. They're people like you and me. Let's behave like adults when it comes to our personal preferences.