"Your point? It warrants a mention, it's just that nobody wrote it down (yet?)."
The point is we've got two different standards in use when it'd be easier for info-finding to use one.
"Walter West is... well, I'm not entirely sure of his origins. But note that the designation was given in 2009, well before we had any clear policy on the matter. Prime Earth is, by editiorial decree, a new universe/multiverse. The Nail is an Elseworld (much like a What If?)."
The Nail is specifically a world of what happens when there's a slight change to the base timeline, that is the concept.
We've got three cases where it's done this way.
"The benefit is that it is, from a historical perspective, ACCURATE."
From a historical perspective, it's innately a completely different history.