There must also be a component of getting used to it at some point, but several people who killed someone (often with the sponsorship of some country that can socialise the cost of war) found their first experiences to be traumatic.
https://en.m.wikipedia.org/wiki/Antisemitism_in_Christianity
Their point holds because there are numerous societies where killing is viewed as immoral but which make an exception for their soldiers performing their duties. Do you have an actual counter-argument or are we just using reddit memes as dismissals now?
Your first comment under a throwaway account framing the argument at the level of reddit, are you kidding me?
https://news.ycombinator.com/item?id=24197646
[1] How plausible is it? Bulgakov's novel is opposite to most which touch on this theme, in that its genre for the present day scenes is magical realism, but its genre for the pilate and christ scenes is hardboiled.
Well the moral and good men in WW2 would never even thought of killing.
But then they were ordered to, and because everyone said "it's ok to kill" this taboo of killing was suspended for the few years of the war.
So our morals are obviously complete relative to what most people around us are doing.
Kill a random guy in 2010? Murder. Kill a random guy in a way in 1945? A pat on the back and the medal.
From a biological survival standpoint "beeing good" matters only "within the tribe" because that is how you stay alive and thrive.
But if the tribe would trive better as a whole if you murder the opposing tribe then that is also "being good".
If morality is rooted in brain science it merely means that it's not absolute, but relative since brain changes if evolution happens.
Today's goods are tomorrow's evils.
And then there are doctors and academics who say we should dump chemicals in water to artificaly increase "altruism".