We use several ways of comparing potency in conjunction. Besides layers, there is also amount, scaling and quality to consider.
E.g. in Inheritance you have statements and examples of certain people being better in mind combat than others. Those aren't layers, but still clearly higher potencies of mind manipulation. Similarily amount of people mind hax is used on is relevant for that verse, as it is clear that more people are harder to mind hax than few.
An example of quality would be On a Godless Planet's resistance negation. Their attacks are so unresistable, that resisting them causes a logical paradox. That is qualitatively better than just basic resistance negation.
Not even all layers are necessarily equal. In some verses those of a lesser layer can still use hax on those of a higher to a minor extend, while in others its complete immunity.
To that come things like mechanism considerations.
Basically, comparing resistance and hax potency is hard and one should go into more detail than just slapping a number on it. It really wouldn't hurt to put more explanation in if one already bothers to do it.