Excuse me, but sure it’s good for your own team if mercy does a 5 player rez, but if you were on the enemy team? You would be screaming bloody murder, especially if you were D.Va or Reaper and you just got 5 whole kills. That’s why Blizzard took it away, because it was annoying to the enemy team and pretty much too overpowered, then Mercy would steal POTG’s that other people worked hard for.
I agree that Blizzard shouldn’t have nerfed Mercy so much to the point that her rez is super slow and that she can only rez once super slowly during her ult, but 5 man rez? I doubt Blizzard will bring it back.