First they had to contact the enemy: Imagine John Cleese in a Monty Python skit: "I say, old chap, would you mind holding your position while I zero in on you? You will? There's a good fellow... and awfully sporting of you, I must say!"
True, but I don't believe most combat troops in the field had scopes on their rifles? Right?
If we're talking about rifles with scopes I would guess that that was for snipers? Or in stationary situations where the shooter had time to set up? As you point out, a scope is utterly useless for a firefight/combat situation. So why have one on your rifle?
If you
do have a rifle with a scope I would think they'd zero in first? They're shooting at stationary targets and not engaged in a firefight type situation.