Guys!!!
Y'all are missing the point. Spray and pray is a well-known ammo waster. Haz seems to have stumbled (Hazaritas involved? ? ? ?) across one reason why.
What you see with spray and pray is part of the transition from aimed single shot infantry weapons to the advent of the select fire or full-auto infantry weapon. In Korea, we had M1 Garands, M1 carbines, and BARs in SAW role. In Nam - a short decade later we started with M-14s and transitioned to M-16s.
As mentioned previously, it has value in keeping peoples' heads down allowing other troops to feel out the enemies' strength and find an alternate path around them. And it has changed squad level tactics too to deal with the volume of lead coming down range. I remember reading Blackhawk Down and being struck by the comment that when moving down and alley you do not hug the walls that formed the alley. When the BGs shot at you, the bullets would all cluster and travel down the surface of the wall, negating the spread of the spray and pray somewhat. A foot or two out from the wall was much safer.
There is a reason why many modern automatic weapons are now select-fire to 3-round bursts rather than full-auto. Lesson learned.