Wano, a country coveted by the government for centuries, has never been conquered by the World Government. Currently, it's Kaido who instills fear in the World Government to such an extent that they have never been able to conquer Wano or challenge Kaido. Shanks can enter and leave Mariejois, speak on equal terms with the Gorosei, halt a war to which he invited both the Marines and Blackbeard to face him. He can stop Kaido, the monster, and Big Mom, with strong ties to Elbaf, almost managed to bring the power of the most powerful nation to herself - the giants, something the government couldn't achieve. And of course, there's the vast empire she has built.
Whitebeard, according to Sengoku, the Fleet Admiral of the Marines, had the potential to defeat the entire Marine force (soldiers) + admirals + Shichibukai + Pacifistas + Garp + Sengoku himself. Blackbeard, aiming for world domination, with a special lineage, possessing two Devil Fruits, something abnormal for anyone, and being hailed as the king of intellect, Luffy is the damn nika, the sun god, a god is a Yonko.
In my opinion, the Yonko ruling the world, that's the reality, they are the lions of the manga.