What's the point in killing 8 guys in a row if you can not prove it? It does not discourage egotrips, it encourages less play from fun gamers (gamers who solely play for fun).
Fun is something personal and subjective. For me it would be more fun if there is the thrill that I am not sure if I killed that sniper shooting at me and my comrades from that dreaded window in that farm, so we must carefully advance, supress the hell out of him, storm the building and check room by room if we killed him.
But as you can check this is a polemic subject, Toddel will make my life hell if I propose this change