These weak attempts to try to downplay Zoro strength and his feats are pathetic.
It's like all of a sudden having conqueror, awakening, and top haki (whatever that is) makes you the strongest fighter in one. The true is having any of those powers doesn't automatically make you stronger than somebody who does it.
King is stronger than Katakuri, Marco and Doffy. King has top defense, speed and element (fire) power. His fire power was like magma. Marco can't beat King and he has top healing powers.