When the player or other group members spot an enemy (or any unit) and call out the position, the position is relative to the 'center' of the group. If you have group members who are far away from the rest of the group all of the position callouts become useless and nonsensical. You could have an enemy right next to you and it could be called out as over 1km away depending on the placement of your group. So for example if you have a sniper on overwatch, a medic waiting back in an ambulance, or any other of the infinite situations that arise in a sandbox, you get to listen to this nonsense.

I don't remember this issue in Arma 2. In fact AI on overwatch would advise you of enemies and would reveal their position in relation to you! Likewise the player would say '50 meters from me' or whatever. {F22516}