Tracer is “so good” but also Kiriko, Illari, Dva, Brig meta… so in my opinion Tracer is not that good, very easy to deny pulse bomb and damage from her.
Tracer just allows players with insane ceilings to realize them. An average player going tracer into an anti tracer comp will look bad, tracer by herself is not crazy strong, but when you're one of the best in the world you can make her work almost anywhere.