My guess is there’s an evolutionary advantage to being able to remove others from human considerations. It works at the group level and overrides the personal. When I was fired from the college without notice or rights it was pointed out to me by people who I consider normal (and actually known to me as empathetic) that my designation as a “casual” allowed the organization to treat me like an object.
These were not crazy people, only people who at some level were permitted by a form of social logic to simply bypass considering me as belonging. I think we reach that level of disregard before we the level of empathy and it allows us to preserve the more evolutionary advantageous survival of the group.
Maha I think you are right to call this a loss of humanity but maybe only at the highest level where we would sacrifice everything, including our own survival rather than cut someone from the group.
In the book “Three Day Road” by Joseph Boyden the main character is a First Nations man who becomes a sniper in WW I and the conflict of morals over permitting a group member to kill others. In the book it is actual killing and maybe organizationally that can translate to removing someone as a group member but I bet it involves the same part of the brain.
Nothing I’ve said justifies the act of De-humanizing people.