In the following sentence, the “and/or” seems odd in a case of total negation:

Evidently some people are not able to interpret and/or analyze at that deeper level.

Because the sentence says “are not able to”, total negation would seem to unambiguously require “or”. 

In a positive sentence, “and/or” is sometimes used to mean inclusive OR (although perhaps OR alone could suffice), but is there any possibility of ambiguity in total negation? 

In other words

Not X and not Y = Not X or Y

Would “not X and/or Y” ever be required? Or does such use merely reflect the increasing proliferation of superfluous “and/or”?