Because no one gives a shit about Kaido. At best people can say oh no one except moria and Ace went to wano because of his presence,which okay, whatever. Wano has been isolated for centuries. But no one thinks of Kaido as a relevant figure outside of wano. The wg let's vegapunk live 5 mins away from him,meaning they're not even worried about him pillaging or looting egghead, let alone starting a world war, in Elbaf they never dealt with Kaido, when the marineford war happend shanks told him that he's not allowed at the party and Kaido ran away. Afterwards Blackbeard easily becomes another Yonko without ever dealing with Kaido ever. At the end of the day,he dedicated his life to selling seastones to the WG and there's no reason to care about him aside from that