The enemy diversion you are ignoring is the main attack. If you're short of everything except the enemy, you're in combat. Incoming fire has the right of way. No combat-ready unit has ever passed inspection. No inspection-ready unit has ever passed combat.
Teamwork is essential.
It gives them other people to shoot at. If the enemy is in range, so are you. Tracers work both ways. The only thing more accurate than incoming enemy fire is incoming friendly fire. Radios will fail as soon as you need fire support.