I agreed in a scenario like a near ambush (can see the enemy within a football field distance) yes. But what about a scenario where one's unit mission is to knock out a single enemy bunker? Each squad within a platoon size unit would bound, cover fire, and trying to out flank it. This is where a low crawl is useful as the lower profile will help the flanking team to sneak up on it from the side meanwhile the enemy bunker is too busy firing at the fire support team to take notice because of the noise, smoke, and adrenaline running.