"
Devil Fruit abilities (Buso Haki has been stated to be able to block devil fruit abilities,
[57] seen when
Doflamingo blocked
Trafalgar Law's Amputate
[58] and when
Trafalgar Law stated that his Shambles ability would not work against those with superior Buso to him
[59])
Heat Manipulation (Sanji states that Buso assists him in withstanding heat
[60])
Resistance Negation (Users with
superior Buso can resist the affects of Haki negating their resistances, shown with
Gear 4th Luffy negating
Doflamingo's negation of
Luffy's resistance to physical attacks
[37])"
One Piece res neg involves buso slop, nullifying devil fruit stuff, etc based on what's actually written out on the various profiles.
This, does not enable them to just negate any resistance ever, it's situational, circumstantial, and involves an energy system of sorts. Akainu wouldn't be able to just negate Superman's heat res for example, because the reason he has that resistance has absolutely nothing to do with the mechanics of how Haki can mitigate someone's resistance to begin with.
Context is key, mechanics and details matter, literally just use common sense and ask yourself how stuff works instead of just taking the title of an ability at face value.