ARAM game mode next patch

Does anyone know the rationale behind banning GA? I can understand every other rule to a degree, but why GA would be overpowered with this setup is beyond me. I really hope this isn't the new game mode supremacy though, as I find its added value to be a bit lacking then. Going to go play the tutorial now just to see how proving grounds exactly was again, hehe.

Proving grounds is just a map with 1 lane, which is what ARAM is supposed to simulate. A GA is OP because after a team fight, a lot of times the winning side is low HP while the losing side got aced. If someone got a GA, then it's possible for them to 1v5 them. It's the same reasoning revive is banned.

You can think of a GA as being 1/3 a revive.