Yea i know.

This mind experiment doesnt take into acount 2 very important things.
1) Soldiers are not stupid, they rise shields when arrows are coming.
2) When you shoot with many arrows to many targets only small portions hit target directly from front. Many will hit from left or right side.
Look at soldiers on left and right of marked soldiers. They are more exposed.
Other issue is that when you kill soldiers target gets smaller and smaller.

So number one decreases casualties and number two increases them.
There is now way we can take this into accout.
But with reasonable margin of error (like 50%) i would say that its possible that this two factors can cancel each other out.