Let's say Person A brings his IS-enabled camera out, but his main intention for getting out of the house isn't to embark on a serious outdoor photo shoot. He might be meeting up with some friends or etc. Along the way he sees a shot that he wants to capture. However, he needs a slow shutter speed in order to get the shot and he does not have a tripod on him. Therefore, he tries his best to take the shot with IS on.
Person B, on the other hand, knows that he is going to need to shoot at slower shutter speeds for his shots. These shots will/might be important to him. However, he does not bring any form of camera support out. He then attempts to shoot, hoping that the IS saves him.
I think what Kit means to say is if you know you are going to need the tripod to shoot, why compromise on quality results by refusing to do so?
On a sidenote, 4-stop image stabilisation is quite powerful :bsmilie: