Because he is that, a swordsman...
...I think it is more fitting title than just calling him a man. The highest decoration in a Sword Piece belongs to supreme swordsman.
Have we gotten proof that Ryuma forged Shusui black? No... Is there any reason to doubt them forging their blades black? None except agenda.
So let me reduce this to a few straightforward questions:
- Can you show the panel where Zoro says he wants to become the strongest human, person, creature or living being, without the qualification “swordsman”?
- Can you show where Mihawk is called the strongest character overall, rather than the World’s Strongest Swordsman?
- Can you show proof that Mihawk personally turned Yoru black?
- Can you show proof that creating a black blade requires the strongest Haki in the world?
- Can you show proof that nobody stronger than Mihawk can exist without invalidating Zoro’s dream?
- Can you explain why Mihawk’s qualified title must be expanded beyond its wording, WHILE Whitebeard’s and Kaido’s broader titles can simply be dismissed?
If every answer requires another interpretation, assumption or appeal to what the story “must” mean, then you are really not deriving your conclusion from evidence. You are starting with “Mihawk is the strongest” and constructing enough speculative bridges to arrive back at it.
At some point, the fact that none of the decisive premises can be demonstrated should make you reconsider whether this is textual analysis or merely an agenda being reverse-engineered into the manga.
With all due respect, this is all a conclusion-first argument:
1. Zoro must become the strongest character.
2. Therefore Mihawk must currently be the strongest character.
3. Therefore Yoru must prove Mihawk has the strongest Haki.
4. Therefore Mihawk must have forged Yoru black.
5. The evidence that he forged it is that nobody has explicitly said he did not.
That is a mixture of begging the question, argument from ignorance and narrative wishful thinking.
Mihawk’s actual title is World’s Strongest Swordsman. You are removing the limiting word “swordsman” and claiming his real title is effectively just “the strongest,” because that better fits your conclusion. Yet Kaido’s and Whitebeard’s explicitly broader titles are dismissed as rumours or outdated. That is special pleading: Mihawk’s title is interpreted as broadly as possible, while every competing title is weakened as much as necessary.
The black-blade argument is just another stack of unsupported assumptions:
Yoru is a black blade -> Mihawk personally forged it black -> blackening requires the world’s strongest Haki -> therefore Mihawk has the world’s strongest Haki.
None of those transitions has been established. “There is no reason to doubt it” is not evidence; it merely shifts the burden of proof.
And saying Zoro’s dream would otherwise “lose its meaning” is not proof either. Zoro wants to become the world’s strongest swordsman, not the strongest living being through the technicality of using swords.
So the reasoning is ultimately circular: Mihawk must be the strongest because Zoro must surpass the strongest, and Zoro must surpass the strongest because Mihawk is his final opponent. Everything between those two claims is speculation being presented as confirmation.
Why should anyone who does not already share the agenda accept that?