Jeff Kaplan said in an interview:
“I think the game gets in a very dangerous state when we tell you who you’re allowed to play and not play with the game functioning like it does right now. The allure and the fantasy of Overwatch is there are these 26 heroes, and you can log in at any moment and be one of them. We should be trying to keep them all viable, and all decent picks within a team composition. I mean, sometimes you’re gonna be countered, but we can’t leave it at other players’ discretion to decide what you should be doing.”
That straight up means that ALL one trick characters are allowed. It doesn’t make tracer toxic.