Rylai's and Zhonya's

I feel as if the reason Rylai's was such a good item for mages was that it gave so much AP and Health and slows to keep hypermobile assassins still since mages don't really have any other defensive items other than Zhonya's and Abyssal. I would almost always rush a Rylai's against someone like Yasuo, Zed, or Talon because the Zhonya's is only good if your team peels for you. So how come ad champs have for mages while Ap champs only have . I would build Rylai's because I needed the HP item to survive their combo. By the late game the 45 armor on Zhonya's would be almost irrelevant since many of the ad items have lethality as well. That and the 100+ Mr that assassins could receive from the items will be more relevant than the 45armor mages get. Since Rylai's was used on so many mages so often guess they are also getting a nerf on AP.