During the Saurian Finality meta ArtifactHai was the second most played deck next to Finality yet so many people were playing it not because it was broken, but because it was one of the only decks in the game to counter the Degenerate deck that was dominating the Ladder at that time. The fact that after Finality got nerfed everybody quit playing ArtiHai just proves that Arthai was not OPed.
Also, ArtifactHai never was and is very unlikely to ever become the №1 deck in the game do to how simple it is to counter it.