Earlier quoted context omitted.
It’s not either/or. The psychological shit is real, but the physical damage to the brain is real also. Both things are true.
> It’s not either/or. The psychological shit is real Depends, because we had millenia of wars, even much more gruesome (but without explosions), and much fewer accounts of psychological shit. It was just a fact of life, and most people carried on.
The aristocracy generally fared relatively well in medieval battles as it was more profitable to capture a noble unharmed for ransom than to risk severely injuring or killing them, not to mention the class taboo and difference in training and equipment between a noble and a commoner.
But warfare was also extremely different. The use of crossbows against Christians was banned by the Catholic church because it was considered too horrifying because of its speed. Battles would often be won by forcing the other side to surrender or morale breaking down and being routed. Because the violence was also much more direct than the pull of a trigger or press of a button, humans were also much more hesitant to actually try and kill their opponent. The crusades are infamous because they actually involved a more modern level of dehumanization but throughout most of history wars would be fought against people who looked like you, spoke a similar language and shared a similar culture. The exceptions are so well-known because they were rare.
"It was just a fact of life" is something we say about all kinds of horrors of the past. You say "most people carried on" but this is literally survivor bias: most people who served in past wars don't go on to kill themselves even without treatment even when they suffer from PTSD or shell shock or whatever. That doesn't mean recognizing and treating their condition wouldn't drastically increase their quality of life. It also ignores that "most" is not all. People would simply starve themselves to death or go into the woods and never come back or get "battle frenzy" and throw themselves at the enemy with no regard for their safety and that too was "just a fact of life" but today we would call that suicide.
History is full of "psychological shit". We just lacked the understanding of psychology to properly classify and recognize it in ways that would allow us to address any of it.