Kaido's hype is shaky. Oda on his own accord chose to differentiate between regular hearsay and actual titles. Nowhere in the canon material has Kaido been referred to as the actual WSC, there are always nuances being made to sway away from it.
Notice in the above panels how it's hearsay and a rumor, the same type of rumor like Luffy being a 25-foot-tall monster
Moreover, there are clues laid out that Kaido in fact might not be even human, and thus his supposed title should have no bearing on humans.
In addition, Kaido, in canon material, has only been referred to as the 'King of Beast', on multiple instances, whilst never referred to as the WSC
Now, I'll present a direct comparison with both Mihawk and Whitebeard. I won't elaborate here, because I've written everything in the panels themselves.
The quotation marks appear in the raw Japanese as well
And no that
sbs did not confirm anything. That is the official Viz translation. Even though they are similar, there are small nuances that make it different, such as 'even Kaido' not appearing. Moreover, Oda says world's strongest creature, not living being. In addition, he leaves no doubts to a mother actually being the WSC. He highlights it by saying she is stronger than Kaido, the supposed WSC, and she is thus the actual WSC. There's no room to debate about anything concerning the mother, as opposed to Kaido.
Oda, on his own accord went out of his way to make a distinction.
Now let's talk more about betting on him in a 1 vs 1.
Kaido and Linlin haven't seen each other in decades.
WB hasn't heard Shanks' name in years implying that Shanks didn't fight any remarkable foe after Mihawk: not Kaido, not Linlin and of course not Whitebeard.
Now for WB.
While it is true that Whitebeard possesses a magnanimous attitude, there is one thing he holds on a higher pedestal than that, and that's his crew and their lives. He was ready to wage war against the entire world in order to get back one of his crew members.
The reputation surrounding the WBP is that if you mess with one of their own you pay for it. Anyone who lays a hand on one of their own should be prepared to face consequences.
The only exemption from this, that we know of, was when Ace first tried to pursue Teach. Key word here being pursue.
however from the supposed implications of Kaido challenging the other Yonko, it appears that he goes after them in order to do so, not the other way around. Therefore, Kaido would have to seek out WB, completely opposite to what Ace did with Teach. Had Teach waltzed into WB's ship he wasn't going to leave that place alive, as it is later confirmed in MF and during the meeting between WB and Shanks.
When Shanks and WB met, WB stated his crew calls for vengeance and that Teach needs to pay for what he had done
In MF WB stated he will avenge Thatch and that Teach will pay with his life, even Teach himself was afraid of dying to WB
Now you might be wondering why I brought all of this up. It's to preemptively stop the WB and Kaido were crew members thing. It's widely known that pirates in the Rocks group vehemently disliked each other, and were killing one another constantly
there wasn't a bond between them like between other crews. Moreover, Kaido was merely an
apprentice in the Rocks crew
meaning he was very young and had spent significantly less time with WB, not to mention things point to bad relationships between the crew, than BB who had served under
WB's flag for decades
The point I am making with this is that WB was ready to kill Teach, someone he called son, someone who had spent decades with him, to avenge a fallen comrade and crew member, as illustrated above.
Kaido is not only the one who killed the man WB himself called his little brother
but also the man who took over his country. We also know that WB is protective of his friends' countries, as he protected FI as a favour to his friend Neptune
From what's established about WB, him letting Kaido waltz onto his ship would have to result in Kaido's death. Therefore, logically playing out that situation, from what we know of Whitebeard and how he treats those close to him, going to such lengths as to battle the entire Navy in order to rescue one of his own, it would defy the established behaviour if WB just let Kaido go after beating him.
Even if we were to say that he fought WB, it would result in his losses, thus not helping him with the people say you should bet on Kaido.
I wouldn't be surprised if the rumour about Kaido started when he defeated Oden, without people knowing he used a cheap shot and underhanded tactics, as Oden was hailed as very strong, even had a bounty, and him taking over Wano, hailed as one of the strongest nations in the world, so much that the current FA of the Navy was more worried about the forces in Wano, rather than two of the Yonko when Kizaru offered himself to go there.
Kizaru was only stopped by Akainu due to the unknown military force in Wano. I stress again Wano, meaning Kizaru was gonna go to Wano, not somewhere along the way but Wano. The rumour was made more believable when the people saw Kaido beating people like the SN, and adding them to their crew. Whilst the SN are far away from crème de la crème of OP world, compared to the general populace of the OP world they are pretty strong. Kaido is the easiest Yonko to get to. He himself seeks challenges. Compare that to people trying to invade WCI and having to fight the commanders
Shanks who travels often and his whereabouts are hard to find. People would see Kaido beating strong people, strong as in stronger than the general populace, but nowhere near as strong as top tiers in OP, and thus start the rumor like that.