Which is what I said. Magic was A factor (one of multiple) and not THE factor (singular). But I guess that went over your head.
Emperor and I don't always agree, but this, according to all the lore, is true.
Magic wasn't the deciding factor, but it was the equalizing one, and the one that turned the tide, but wasn't the only factor. There were many others. Like it was the first time all the nations of Thedas worked together, so they had numerical advantages, differing combat specialties and so on.
Also, wasn't Tevinter, the land of magic is master, on of the first nations hit? They would've used magic from the get-go, even if they never lost their capital city of Minrathous, they have a strong stake in Seheron.