This point of view is based upon the notion that in every conceivable tactical situation, your foe will always be bunched together.
Unfortunately, in real life situations, this will not always be the case.
Are we then assuming that if faced with a number of men who disoblige us by not bunching together, we might then ask them to kindly bunch up so that we might hit the guy next to the one we were shooting at?
True, barrage fire at a mass of men is an important application, but not at the cost of an inability to shoot accurately at a moderate distance.
Another very real benefit of practising for accuracy at 100 is that it will make you more accurate at longer distances.
Rod.