And it makes sense when you fully understand their training and how they were attached to Marine Company's. The Snipers were not attached to the Rifle Squads on the front lines. The Snipers were part of the Headquarters Platoons. So the major focus in Sniper School was intelligence gathering and map reading. With the fact that most terrains weren't effective for a sniper rifle, and they were already attached to Headquarters, it really makes sense they would have been used for their intelligence training. They were more effective that way.