5.16 armor Nerf but BUFFING MAGIC RESIST?

nerfing juggernauts, nerfing tanks, nerfing armor but BUFFING MAGIC RESIST? seriously mages do next to no damage to tanks, at least the adc's armor pen will be more effective on them but the few magic pen items you can get are not enough. the buffed armor and hp growth on supps helps tho. also R.I.P MORDIKAISER MID he was a good ap tank