A few patches ago ADCs did. I'm not sure Kench, Alistar, or Braum (21st, 4th, 8th best performing support) are 'ruining games' since Janna, Lulu, and Nami (1st, 2nd, and 3rd best performing) are already 'ruining more games' if you count just winning as ruining the game.
I mean a support doing his job isn't ruining games. I know it sounds way better if you say they're ruining games, but I'm just not convinced that they are really warping any meta since it seems to be enchanter supports atm.
Finally, relic shield is used on mor ethan just Kench, Alistar, and Braum. Let's just accept for the sake of debate that they are ruining games. It would make more sense to nerf those champions individually than a more global nerf to supports like:
(I only really see Alicopter play this one tbf).
That being said GP is the real reason that Relic shield is getting nerfed. He's just abusing it top lane for the HP, HP regen, and the bandit passive on Q / exploding barrels for more gold.