It’s not exactly that they consciously want cover to commit atrocities. It’s more that they can’t really conceive of people they don’t identify with as people. They’ll fiercely defend people they know, and they’ll side with people like them, but everyone else is a sort of vague abstract mass.

We see this in the US today with people who support harsh measures against illegal immigrants while they themselves have friends or family who are the targets (or they are themselves). Then they get very confused when their friends or family get arrested and deported, because “illegal immigrants” is this amorphous mass of bad people, not Jose and Clara down the street. You see it with racists who defend themselves with “I’m not racist, I have black friends.”

Such a person doesn’t automatically think ill of the “other,” but it doesn’t take too much to convince them that the “other” is evil and dangerous and must be dealt with harshly.