I doubt we're going to manage to reach any kind of synthesis here; "all attempts [...] are misguided" suggests to me that you won't be satisfied until I retract this entire post and recant my viewpoint completely. Which I won't do, because although your points about overlap and interaction are entirely reasonable I don't think they invalidate the entire approach. The dividing line is certainly pretty fuzzy, but that doesn't stop it from being a meaningful concept: many concepts without a sharply defined boundary are useful concepts nonetheless.

In particular, I disagree that in practice most or all decisions have so much intermingling of both sides that it's impossible to tell where any given impulse came from. I think in many entirely practical cases, it can be pretty clear one way or the other.