If the bit gets caught in the piece of metal you are drilling, it will most likely spin in the chuck. In rare cases though, you tightened the chuck up real good, and the actual drill press swings around.
Its more of a safety precaution than anything else.
I do agree that you should bolt your press to the bench, but this is not a reason why. To prevent this from happening you would bolt what you are working on the the press's table. Trying to hold on to what you are drilling into instead of clamping it while using a drill press is extremely hazardous.
my main message.
Thanks for clearing that up guys

