No, the accidental purpose is not just an abstruse brain bender. Its intellectual value is a practical description of objective reality: whether we can actually solve political-economic problems or not, and what the liability really is associated with identifying problems and creating effective solutions on demand.
Look at the Periodic Table of the Elements, for example. It has a clearly identifiable mathematical symmetry. What we naturally understand is that nature is logical, knowable, and predictable.
Numbers are nomologically predictable. They are conditional, imperative, and sometimes irrational. The square root of 2, for example, is not rationally 1. If it was, then, well, that would be irrational! The irrational quotient is logically positive, nevertheless, and the square root of 2 may be 1 in another universe (but I doubt it!).
There are some things we know to be categorically true, and like Kant said, because it is a natural identity, we are obliged to it. The imperative value may be different in another universe (but I doubt it!).
If I mix A element with B element and C is the product every time, like Kant said, it is a strict liability. We are naturally obliged to the combination of those elements and the value that derives from it on demand.
The question is, then, whether the derivative value (the natural effect) has the attributes of existing on demand. That is: whether its purpose is accidental or not.
Given an infinite amount of time, functional attributes can derive without purpose. These “emergent properties” can then be described as having useful value, and in the realm of political-economy Objectivists, for example, contend there is no real obligation to the apparent ambiguity. Having a naturally accidental purpose, the liability is strictly limited to what we can actually know, isn’t it?
Is the emergence of the Sanders campaign really accidental (and thus surprising), or a real cause with an actual purpose that can be reasonably described as an approximation of objective reality ontologically derived on demand!
Real cause without actualizing purpose may exist in another dimension (but I doubt it!).