Long before there were video games about people shooting one another in war, there were wars with people shooting one another.
The reality of those wars, the constant fear of death and gruesome nature of battling for your life still had its own unspoken rules. And as in video games, it seems that those who fought were never fond of snipers.
Snipers were detested and feared as much for the strain that they caused to men's routine movements in forward areas as for the casualties that they inflicted. Their activities provoked as much irrational resentment as the killing of bailed-out tank crews or parachutists in mid-descent. Both sides habitually shot snipers who were taken prisoner. "Brad says he will not take any action against anyone that decides to treat snipers a little more roughly than they are being treated at present," wrote the First Army commander's ADC in his diary: "A sniper cannot sit around and shoot and then capture when you close in to him. That's not the way to play the game."
Fucking Campers [Reddit]