Half?

Let me paint you a picture.

youre tracer. Youre the best flanker in the world. You run, dash and kill. You see a solo Roadhog. You burst, you dash, you recall, he heals, 300HP! You burst him some more, dash, avoid his hook, you have to be fast, his astma inhaler will be off CD in a few seconds, you get him down to 100hp, inhaler is off cd, 400hp, you retreat, but you have ult! You blink towards the fleeing hog, sticky him and burst him down, he dies! You retreat cause that was one hell of a battle. Mercy swoops in and rezes the guy like it wasnt even a thing.

You literally fought a pitboss by yourself, did over 1000hp dmg and mercy undid all of it in a blink of an eye.

How is that remotley less of a problem than a junkrat you can dash around and burst down within 2 secs as tracer? Even if he gets revived, you run back and shoot him in the face again.