For starters nothing implicates that a WSS cannot stand as WSM. Second, nothing implicates that the WSS * necessarily * needs to stand as WSM as long as WSM is no swordsman.
For example I'm one of the few who classify Whitebeard as a swordsman due seemingly being the carrier and heavy user of a supreme grade sword, and yet I don't believe he necessarily always perpetually stood as WSM despite the vivre card kept suggesting such notion and that is due his sickness taking over. Titles don't necessarily have to work out in real time, MF profusely demonstrated how Whitebeard was probably no more the WSM.
That being said it is common in a fictional work that the strongest swordsman is catalogued by the author as most powerful as well, not merely best at sword skill. On top of it, it would make sense if Mihawk was the strongest given he's Zoro's final set opponent and as a kid he swore he had to become the World's strongest. Yes he specifically mentioned this, confirmed by Oda himself.
For example I'm one of the few who classify Whitebeard as a swordsman due seemingly being the carrier and heavy user of a supreme grade sword, and yet I don't believe he necessarily always perpetually stood as WSM despite the vivre card kept suggesting such notion and that is due his sickness taking over. Titles don't necessarily have to work out in real time, MF profusely demonstrated how Whitebeard was probably no more the WSM.
That being said it is common in a fictional work that the strongest swordsman is catalogued by the author as most powerful as well, not merely best at sword skill. On top of it, it would make sense if Mihawk was the strongest given he's Zoro's final set opponent and as a kid he swore he had to become the World's strongest. Yes he specifically mentioned this, confirmed by Oda himself.
So if you accept Mihawk as the defacto WSS, you have to accept Whitebeard as the defacto WSM. If you argue in favor of one, but against another, your biased opinion is no longer valid.