I think having a scoreboard would greatly improve Overwatch for nontoxic players.
The MOST important difference would easily be that players could see how often their vulnerable heroes were being killed. I believe this would cause less toxicity - as I can’t image many people would blame an Ana for not healing if they could track how often they were being attacked throughout the game. Ana can’t defend herself well, so she needs peel.
Peeling in a random matchmaking setting would be MUCH easier. Additionally, you could tell when it’s one player struggling a lot, or an enemy player DOMINATING. Maybe it’s not even that your Ana is that vulnerable, but instead it’s the Genji who’s having a really good game. This helps! It reduces accusations! Right?
At least make an experimental gamemode of it. I would bet my monitor that people would generally accept the addition. Plus it takes way less dev time than other solutions to toxicity.