I found the delocalization of killing a pretty big difference. I think most of war is justified by the fact that you're risking your life on site, a distorded 'kill or get killed' excusing the its absurdity, the emotional rush of surviving makes the act acceptable for some time. On the other hand, sitting comfy at home and triggering death is a pretty dissonant concept that makes people rethink being at war. Often veterans run away from war, with time they concluded about its nonsense, here people experience this right away.