There’s only one entrance to the house: a steel door two feet thick. If someone from the outside touched the door—even with a battering ram—they’ll get an electric shock. No bad guys could get through, right?
Well, suppose the bad guy tricks the homeowner into opening the door…and once open, the bad guy strangles the homeowner. Do you see what happened? All that security is worthless if the homeowner can be tricked. And the same goes for passwords. You can have the longest, strongest, most gibber