It's not a bad theory but, if true, shows the writers did not understand the Age. The Dark One has been touching the world since the Bore. Ishmael was loose for 3000 years. The world had steadily decayed for the entire period from the Age of Legends, to the Ten Nations, Artur Hawkwing, to present. It was Rand, as the Dragon Reborn, that changed the decline.
So, the world was steeped in growing darkness until the Lord of the Morning returned.