Can someone explain the logic for scaling?

[ObberGobb]

What I mean by this is: is there any actual consistent logic for scaling outside of calls? For example:

MCU Iron Man is listed as the same tier as Thanos because he was barely able to draw blood from him. At the same time, Akainu (One Piece), is only at High 7-A, despite easily blowing half the face off a 6-B character. What is the logic for this?

 

[Purgy]

Durability negation as it says on Akainu's profile.

And if you want to be technical, Whitebeard doesn't have a single durability feat anywhere close to 6-B, in fact, he took damage from basically every attack that hit him and was repeatedly stabbed by essentially fodder marines.