"Stunned" isn't really a scientific term. It's the sort of editorializing you should expect to come from people who aren't the scientists themselves. More than hyperbole, it is classic click bait.

Also, quitting smoking definitely eases a number of symptoms, especially if you're not at the point of chronic emphysema. The reduction of inflammation triggers alone after a bit of time is fairly significant. Less coughing, less mucus buildup, etc.