How was it a good idea?

Also if you don't know turrets scale to maximum of 30(!) magic resist and armor. They used to have 100 of both. In Riot's defence they do have more health but without those resistances they simply melt faster than before. Last but not least inhib turrets and nexus towers up to 31 minutes into the game have 0 armor and mr. So if you were wondering why games are so ridiculously snowbally this is one of the reasons.