iOS7's transition to flat design was behind both Android and Windows 8, and clearly followed them. I think the point the author is trying to make is that Apple,

iOS7's transition to flat design was behind both Android and Windows 8, and clearly followed them. I think the point the author is trying to make is that Apple, the biggest proponent of stylized, squeomorphic design moving to flat UI behind Google and Microsoft was really the final defeat of brushed metal and rich leather in UIs.