exploitable bugs or things that just don’t make sense to be in place or that don’t impact the balance of the game
I would debate that it, indeed, does not make sense to include a consistently inconsistent occurrence in which a player is denied an ability granted to them by their composition simply because of an arbitrary overlooked piece of code.
I would make the bold statement that this is indeed an exploit, but rather an exploit that works against the player, and would make the argument that it indeed impacts the balance of the game by causing melee characters who rely on weapon procs to be effective (such as paladins, shamans and some warriors) to be literally unable to perform a job that they are attempting solely to perform (apply the proc).