SM OU also has a ton more viable fairies that don't explode vs Bisharp like the Tapus, while ORAS only had Azumarill who still got hurt a lot by losing its item.
But yeah MMO doesn't have Z-Items or mega stones and buffing knock off would just buff the already powerful fighting types even more as they'd get some really sweet coverage with that buffed knock off, while the only dark types that would get buffed are Absol, Weavile, Bisharp and Crawdaunt who all will still mostly get walled by steel types except maybe Crawdaunt.