I mean yeah the Admirals are billions of times more durable than these pathetically weak Celestial Dragons. In a series of characters like Doflamingo who can get shot in the face by a bazooka and not even be scratched or interrupted from his conversation, the pathetically weak Celestial Dragons seem to only have durability relative to irl humans. If they didn’t have hax then these characters could be killed by standard gunfire lmfao.
The Gorosei and the Holy Knights are definitional hax/fruit merchants who also have strong Haki, but they are physical weaklings reliant on demonic power to not get killed by the likes of Mjosgard.
Just imagine if Oda introduced a Celestial Dragon fighter so weak that they didn’t possess Imu hax and devil fruit power, could we even say that such an absolute weakling is worthy of being compared to the Holy Knights?