I think the main point of this excerpt from All Quiet on the Western Front is that war should not be idolized because death and the effects of those who faced it are destructive.
Many books idolize war and make it seem like an adventure. in this epigraph, the author makes it clear that death is not an adventure. It destroys all who have to endure it. Many men die, but even those who did not will forever be changed by the war. It did not kill their body, but changed what made them who they were. They are now just shells of what they once were.