Like I BEEN saying for honestly years now. It’s extremely possible that there never existed a “Yonko” or former WSS/WMWM etc. back then WB was tha WSM and Roger was King. So it’s entirely possible that tha titles and such came to fruition after Rogers death since he held all of those things at tha same time
The concept of Yonko exist since the death of Roger
Even before that, they were always 2-3 rulers reigning
Yonko system became a thing after Roger died
There were always 4 emperors because warlord system existed even 10 years ago (Shanks wasn't even Yonko back then)
Sso why would Navy need 7 Warlords if there was not a 4th Emperor beside Kaido, WB and Roger between 24 - 6 years ago ?
The only answer is that Silvers Axe was the Yonko
Oda already used Wang Zhi to hype Teach
Shiki was a former ruler alongside WB and Roger.
Xebec ruled as King of the seas for a decade before his defeat 38 years ago.
Rocks pirates ruled the seas as rulers or Emperors for the past 50 years
WB and BM : became Emperors 24-22 years ago
Kaido: became Emperor 20-10 years ago
Silvers Axe : became Emperor 20-6 years ago
Shanks: 6 years ago
Teach : a year ago
Luffy and Buggy : a month ago