The M1 Carbine is the standard by which all PDWs are measured.

[stanc]

The Ordinance Department's original 1938 request to manufacturers was for a light carbine to replace both the pistol and revolver. Both are PDW weapons that are normally issued to support personnel , artillery personnel, mortarmen, and officers.

So, the story's statement about the M1 carbine's original intended use is true...

Infantry platoon leaders are officers. They are also front line soldiers, not rear echelon, "secondary" troops.