When you figure out why Yoru is the strongest weapon in the world, you shall be free of the doubts...
Only Yoru is strong enough to handle Mihawk's swordsmanship at it's strongest
We all should have seen the kanji broken down yes? for anyone that does not know, the manga says Mihawk's sword skills, and by extension sword techniques are superior to Shanks
Divine Departure for example has only ever been described as a sword technique, it uses the exact same Kanji. Regardless if it uses Haki.
Therefore Mihawk's sword techniques are superior to Shanks's Divine Departure, by extension this also means:
His sword techniques are superior to Rogers, since Shanks is just copying Rogers swordsmanship, though he elevated it.
Even Oden self proclaimed his swordsmanship as the strongest, meaning by the time he returned to Wano, he considered Paradise Totsuka for example to be superior to Rogers Divine Departure, which it was clearly.