Its still a .410 shell out of a pistol. It just doesn't have the power to stop threats.
Not everyone is thinking meth'd up zombies breaking in their apartment.
I'd think in 9 cases out of 10, simply shooting at a perp would have them running.
And that last 1 in 10 most don't put themselves out there to face.
just a simple handgun is really enough for most. The slide shotgun does have a impact too, but it's also a telltale for where you are at.
IMHO if you have a gun yet no perimeter security in locks, dog, alarm, intruder resistant windows/doors (in that order realistically for most budgets) then you have already failed.
IMHO it's also one's duty if they own guns to have all of the above to keep them from being stolen when they are not home.
On the street, you usually will never have to use your gun...when you do need too again chances are that will be enough no matter how many rounds. I have not heard of anything locally in decades that when one perp was shot the others didn't run away that wasn't a gang vs gang deal or some drug dealer / money launderer getting hit.