The problem with this line of thinking is that this argument can be used to counter literally any in-verse hax scaling that even has a minute possibility of being non-linear.
_______ only has stated resistance to Soul crushing, so even though another ability which pretty much does the same thing can be used on ________, it's a different power in-verse so they cannot be scaled to one another.
Tbf YungManzi
The general principle behind Genjutsu as a whole is more so Illusion Creation Hax more than anything else
Eida's ability has nothing to do with Illusion's whatsoever so you can't say Genjutsu and Eida's ability does pretty much the same thing
While Genjutsu and Eida's ability both affects the Mind, they clearly do so through different means, Genjutsu messes with one's chakra flow to induce a variety of effects while Eida's ability pretty much affects one's subconscious and induces mind breaking because your trying actively resist her power.
There are clear enough differences to show that Eida's power is neither Genjutsu nor operates like one but is rather it's own unique skill
And as for stacking Genjutsu Mind Resistance untop of Eida's ability.... That's a really slippery slope that you would be trying to go up...
Resistance to Genjutsu Mind Manipulation doesn't mean your naturally resistant to every form of Mind Manipulation there is....
Genjutsu Mind Hax resistance is purely and solely through genjutsu which works by affecting one's charkra flow. Eida's ability manipulates the mind by affecting the targets subconscious, simple as that. Eida never overlayered a Genjutsu Based Mind Resistance, she simply Mind Haxed through another means that character does not resist at all.
That would literally nuke verses like Bleach, Reincarnated as a Slime, and even Dragonball itself. (Zeno's EE would not be layered since he's not using Hakai but another kind of EE)
As for your example here with Hakai that the GoD uses and Erase that Zeno uses. Both are admittedly two different techniques but both have the SAME effect of Erasing a Target from existence. Genjutsu and Eida's ability have vaguely similar but not the exact same effects and ultimately achieve there effects through different means. (I mean name a singe time in the series any Genjutsu induced the same effects Eida's ability did). The Hakai and Erase techniques achieve the same effect through the same means, erasing a target's body, mind and soul from existing, with Erase just being admittedly more powerful
This is just my understanding of the situation though