Any weapon used for self-defense is meant to stop the threat. It may or may not kill the person presenting the threat, that doesn't alter the fact that its purpose is to stop the threat, not kill the person of the threat.

Just about any handgun caliber can kill; stopping the threat in a timely manner is another thing altogether and takes more gun than one designed to just kill. Some folks use the argument that professional hit-men/killers use a .22LR as justification to use a .22LR pistol for PD. That's a bad argument IMO. Coldly assassinating someone from ambush and defending yourself in a PD situation are totally different actions requiring different tactics.

Personally, for PD in the home I will almost always go for a 12 ga shotgun, more destructive than any common pistol caliber.