That's a correct, non-obvious and useful consideration generally. Though in the situation I had in mind (explaining "akrasia": the lack of a thing) there are many "explanations" that are truly useful explanations---just not uniquely powerful ones. And in (a model of) a complex system each (overlapping, continuous...) level of abstraction has its own set of ways to fail. (There's probably some kind of relevant point exemplified by our back-and-forth here.) "Irrationality", like "akrasia", is another lack-of-thing with enticing "explanations", and "rationality" is a thing.