User blog comment:Nearthel/Critical Strike and Penetrations overhaul/@comment-5077844-20150620181009/@comment-5077844-20150620220330

Still, IE would have to get nerfed in some way to not make it completely nuts.....I mean, if it gives the same Ad as now AND bonus damage through crit chance AND armor Pen...in just one item.

Basically tanks would become worthless, because there's no point in building armor anymore if every ADC gets armor pen ont her first item