“Someone enters your home knowing that you’re there. Assuming that they are armed and hear the shotgun racked they will either run away or immediately open fire in the general direction of the sound. Tactically it’s a bad idea to give away any advantage that you have.”
I agree that racking is a bad idea if you are in the same room with an intruder. If you are not in the room the odds that they will take a “general direction” shot is remarkably low, and the odds of hitting anything is near zero.
I know of no tactical training schools that teach you to rack the shotgun to scare the bad guy. It might work, but it also might get you or a family member killed.