For me , Oda should have written Luffy's path to PK like this :
Luffy vs kata at WCI
Luffy vs Weevil or Yamato at Wano
Luffy, Kid and law vs kaido in Onigashima
Luffy vs BM at elbaf or Luffy fights an admiral
Luffy vs Teach
Then Luffy vs Imu
This way Luffy solo a top tier only post wano
And kaido defeat will be much satisfying