Mercy so easy only in low ranks.

If you have good move you can do teamkill by mercy under ultimate skill… Especially if your DPS no have damage. In overwatch you should kill by any role, but in healer mode you should don’t die at first, heal you team at second and do damage in third. That’s true less for mercy, because she has damage increase bean and you should change to it for support ultimates for example, but more on Birgit or for new healers.

And with tank too. You should protect your team, know all mechanics and do damage for enemies. For example sigma, you can eat Moira orb and Zarya ultimate skill by bullet protection skill. that is literally black hole. And if tank don’t do that you team in pain. And if you don’t damage targets you team lose.

But Overwatch bad example because that more arcade shooter. Many moves depend by skills, not for headshots. You literally have melee characters without any targeting.