How the heck would men dying make the next generation of men shorter?
If those who are drafted are killed in really vast numbers, a disproportionate share of the children in the next generation will be fathered by men who were not drafted, including those who were too short.
For a similar example, initially WW1 pilots were selected from the nobility. Once those got massacred, the various Air Forces had to abandon that idea, and allow commoners in. The subtext of the movie "The Blue Max" was about that transition.
(The life expectancy of a British WW1 RAF pilot was 6 weeks. There's also a movie about that, "The Dawn Patrol".)
This also happened to the officers, which ended the notion of officers being restricted to nobility.
It's like how fishing for big fish makes the remaining fish population shrink over time.