Personally for Black Widow, Rocket think the balance team should decide whether they want her to be able to one shot or not.
If yes, then they should redesign her primary to fulfill that somehow without the help of a damage buff.
If not, then they need to give her a kit an overhaul. Maybe give her medium range akimbo pistols instead of batons that charge up a meter, allowing her to fire a strong sniper shot once it's full.
Their mistreatment in rivals when it comes to their balancing is absolutely ridiculous when they can be so much more and it’s like the creators refuse to acknowledge it ever.