I think I'm amongst the majority when I say I'd love to see Garchomp OU with Sand Veil banned.
Leftovers + Substitute presents Garchomp with so many rooms for escaping the clutches of death, instantly taking momentum away from the player who deserves it most. By it, I also mean the match as well as other in-game factors which determine a winner and loser.
So, you've missed a 100% accuracy move and reward Garchomp a free turn to set up Substitute, but the score favors you and you just need to break the barrier for a second opportunity to hit Garchomp. What happens? You break the Sub, typically lose a Pokemon in the midst of things, and then miss again because the opponent spends so much of his time abusing the chance of luck that it becomes a likely possibility you will then lose due to untimely, critical misses.
It's uncompetitive by nature, and Rough Skin definitely proved Garchomp was managable and certainly OU material. However, its inhuman characteristics of previous experience come into play all too often because it is naturally one of the "go to" Pokemon in the tier; just now, it's all the more appealing if you're on the losing end of a game and resort to a cheap getaway tactic such as evasion.