​Nothing is a more enticing target than a lone Mercy cut off from the rest of her team. As soon as they see her firing her ineffectual pistol, the enemy team charges down the hallway, eager for the kill. 

Mercy died, as she was sure to, but her heroic sacrifice set up the Pharah for the ultimate surprise attack. 

More like "justice rains from behind," am I right? 

Pharah ult is pretty easily countered, unless you're literally standing behind the unaware enemy team. Zarya doesn't even get a chance to bubble a friend before her Zenyatta and Soldier: 76 both get annihilated by rockets. 

While Pharah gets the kill credit and the highlight, it was only possible through her Mercy's diversion. Without that, there's a chance the enemy team notices the Pharah standing in the corner - or doesn't take the upper route to the point at all. 

Her death was one hundred percent worth it, even if she doesn't get any assists for it.