1) This model consistently explains magic though. We know there are giant warp gates leading to the aethyr pouring the eight winds into the world. That is a fact. You can try and explain how your 4 elements work but we know how the eight winds theory works. It is the basis of basically all magic that doesn't assume 1st edition as canon.
2) It explains the magical traditions of: the High elves, the dark elves, the wood elves, the lizardmen, the dwarves, the Empire, Bretonnia, Tilea, Estalia, the birder princes, Albion, need I go on? The winds based model is the main magical theory and it explains nearly all magic that isn't divine.
TLDR: No the elementalists didn't discover this one weird trick that is a completely new magic tradition that isn't based upon either the aethyr or one of its inhabitants.