To answer those asking about FFXII and FFXIII being here...only thing I can think of is the same reason Gilgamesh shows up damn near everywhere, and is the same one from FFV...Void shenanigans. Also, Allag found a way to manipulate Atomos, which is something to keep in mind. Might sound like a cop-out, but it's the closest thing to an explanation I can think of.