So why is it that Harbor's util slows his own teammates, when Viper's util doesn't decay her teammates? Kind of an oversight.

I wanted to follow this practice routine by woohoojin, but I don’t know what the difference is between the overaim routine at 2:56 and deadzone routine at 3:16. Can someone explain it to me? https://youtu.be/JxP2y_q51IE