Theory time:
The
hannya (θ¬θ₯) mask is a mask used in Japanese
Noh theater, representing a jealous female demon
The
hannya mask portrays the souls of women who have become demons due to
obsession or jealousy
Luffy's main reason to why she wasnt Oden is because she wasnt beloved like him
In the latest chapter Kaido made very clear that she has been all alone for all her life, everytime she befriended someone they would die in some way, mainly because he wouldnt allow it.
So what if Yamato's reason to becone Oden isnt so much because Oden was super cool, but because he was so beloved and free while she is chained and alone? What if Kaido is the whole reason why she decided to take the name of his greatest enemy?