So why did Aramaki say that Kaido's rule kept people away? What is Kaido's "rule" even suppose to mean in this context? He enslaved that country, with even Whitebeard staying out of it. Kaido ruled by strength, that's the point.
Whitebeard stayed out of it to avoid unnecessary deaths, I think Marco mentioned that explicitly. They only learned about Oden 5 years later too.
Kaido did rule the country with an iron fist, if anything the marines were more concerned about the unknown Samurai military force than the yonko themselves. So yeah Wano is pretty much a natural impregnable fortress and guarded by a 30000 strong yonko crew. Kaido himself was a yonko who contributed to the world balance and was supplying the government with weaponry of all shapes and forms.
But yeah the point stands:
-Akainu and Kizaru had no issues with these 2 yonko, the main concern was unknown Samurai force
-He could’ve easily attributed it to Kaido‘s personal strength, but then again his rule in that context was being compared with the new benevolent shogun.
-Kaido was still an emperor who commanded over 30000 troops
-Kaido being a yonko who contributes to the balance
-Ryokugyu having no issues killing someone stronger than Kaido backed by the entire alliance
And now solidified by someone like Lucci, who pretty much has Cp0 intel on how the Nika vs Kaido fight went, having no worries fighting someone stronger than Kaido.
Nothing supports the counter argument really.