People differ. Armies should hire fewer sensitive souls and more minor sociopaths. It really isn't at all hard to spot those that will work out versus those that won't with 90% or better assurance.
As an aside on the subject of combat related books, there are of course exceptions but generally sensitive souls write and exorcise, sociopaths don't need to do so thus rarely bother.
Recall though that for small wars (or Armies...), while such selectivity can be employed, in larger ones the press for more people dictates mass hiring practices engendering an obvious loss of selectivity and thus the acquisition of more rather than fewer sensitive souls -- most of whom will go forth, do their job and be okay afterwards. Some will write books, a few good, some mediocre and some poor.
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