How do you know this? Did you ask him? Did you read it in the story? Oh no, you pulled this out of your ass.
I know this because it is common sense that intro boxes come from the author, not from Morgans, which is something you pulled out of your ass. Funny how you project your own delusions onto me...
You know that characters have to have a backstory, right? You know that there's journey they've been through, right? There's a moment when Mihawk got his title, he did something to get it, or somebody gave him that title. Otherwise, why does Zoro even believe he's the WSS? Clearly he heard from somebody, or read it in the news papers, which means there was a moment in the timeline when he got it, and somhow the entire world got to know about it, which means it spread all over the world in quick manner by some short of messaging–the same way the world found out that Roger became the Pirate king, the news papers spread his achievement throughout the world. How do you think the world will find out that Zoro became the WSS after defeating Mihawk? Clearly it will be spread by someone. Do you know what chronological events even mean? Hell, probably not.
No, the backstory doesn't need to exist. It is entirely up to author's whim whether he chooses to add it or ignore it.
If Oda doesn't add it into the story, all of your questions will never be answered.
lol, you think Zoro becoming WSS will be spread throughout the world? By NewsCoo nonetheless?
What do you think that world is? Interested individuals in the power scaling tournament who read news to find out who's the new champion? Zoro will be declared as the strongest by author's declaration box, that's all. The world of OP couldn't care less who is the individually strongest character, they are not OP's audience that participates in power scaling...
Well, if nothing else, I can't wait to see how you spin Shiryu > WB soon, then.
Shiryu>WB will be the least of people's concerns, if things go the way I think they might go.
Shiryu>Rocks/Blackbeard/Imu might become a thing.
If he is supposed to be the 2nd hardest challenge for the stronger character in the show, he will be something else.