Rotating power tools and gloves will eventually get you hurt, you just have to do it long enough. A glove caught in a grinder could tear up your hand, break fingers, tear tendons or any number of other unpleasant things. This is the same as the loose clothing rule. Everyone who had high-school shop learned these safety precautions because the old machinists with missing fingers figured them out for us.
For what it's worth, I've been hit with 10's of broken belts. Some are less comfortable than others (I have nearly 100 36grit belts who are prone to breaking at the seam), but aside from the scare, they are usually fairly timid as far as shop injuries go.