Those that think there are "Yonko" and "Admiral" levels so i guess power scalers. At no point has Oda ever said a yonko could solo all 3 admirals but so many in the fanbse think they could. its ridicuous.
It mainly comes from Shanks stopping the war, people ignore the fact that Akainu WANTED to fight shanks but he couldnt go against Sengoku. If Sakazuki is fleet admiral at that point in time that war continues.
They also say Sakazuki got bodied by whitebeard, yes Whitebeard got in some great hits but Sakazuki took half his head off and didnt look out of breath or incapable of continuing the fight but everyone says whitebeard destroyed him, no he didnt re-read the chapters Sakzuki was fine.
Aokiji, Kizaru, Garp and Sengoku were all in perfect health, there is no way Shanks walks away from that war unharmed if Sengoku isnt a reasonable fleet admiral who values the lives of his marines.
there is no yonko/admiral level. and top tier fighter can beat any other top tier fighter if things go their way.