Maybe ADCs aren´t broken. Maybe the classes that are just meant to deal with them are weak instead.
Why do you think Riot is buffing some bruisers and some assassins, even going as far as reverting Rengar and soon, LB?
You don´t fix ADCs by gutting them, you fix ADCs by bringing up the power of the ones able to deal with them and give them tools for that, i.e., that shield ignoring/destroying item they´re considering adding.
Of course, they can´t go wild with buffs, especially in regards to the class of balls of stats a.k.a. Bruisers. It´s why Fervor isn´t coming back. It´s why they´re buffing base damage instead of ratios on Renekton. It´s why they´re exploring a Bruiser-tuned, but not Bruiser-exclusive keystone that has almost nothing if not nothing to do with giving them AD.