Kaido was late series filler without high plot importance. He played the role of strong character the mc had to beat to enter the big leagues with the real endgame cast. Oda didn’t even have a design planned for him during enies lobby, and his characterization has been shallow. I’m not denying his strength, but he’s not pivotal to the story.
Kuzan and Sakazuki by contrast have effectively been recurring characters for decades, profoundly shaping the trajectory of the main characters.