Lots of shooters are really surprised at the violence and just how hard people can fight back when their lives are at stake.
Sun Tzu wrote something like. always give your enemies an exit, no one fights harder than with their back against the wall.
I think it is not just desensitization, it is also productization. We have made ourselves products and therefore, we are disposable and without feeling, thought or life of value. We have created a society of strangers, while we discount and treat badly the people who actually care about us.
Nothing wrong with soap boxes, it is good to air thoughts :)