I'm not sure what a "fundamental" breakdown would be, short of the entire game engine somehow crashing, but I'm saying that the consistent ability to damage an opponent on a missed attack – literally, with every missed attack – requires a narrative justification for how that's happening (particularly if it means that you're always connecting somehow, negating the "don't connect with the enemy at all" part of AC, at least if we accept that hit point loss means an injury is dealt). Moreover, that this justification is no small thing, since otherwise it can introduce a disconnect between the flavor text and the mechanics that some players find unpleasant because it brings them out of the immersive aspect of play.