[Suggestion/Theorycraft] Removal of Armor penetration and Magic penetration mechanics

The problem: Defense Nullification aka "counter to a counter". Building health, armor and magic resist has always been about countering lots of incoming damage by making yourself tougher at the cost of offense power. The problem here is they have items like Last Whisper and Void Staff that effectively nullify the value of armor and magic resist to a point that it is worthless, while also boosting offensive power at no cost. For HP there are dozens of counters to those who stack hp like Blade of the ruined king, Liandra's Torment, and even the precision mastery that gives bonus damage to people attack higher health targets. Point is, they have effectively made defensive gear worthless unless it has an active effect worth using, there is literally no reason to build defensive anymore as defense nullification has made this into a 1-shot game.

The idea is simple enough, remove penetration mechanics from the game to defensive gear worth the cost but also be effective. I would say keep Lethality in as it gets outscaled by armor eventually anyways. Obviously we would want to put some sort of cap on Max physical and magic damage reduction (say 50% reduction?) to ensure that the effect doesn't result in ToL (Tank of Legends aka the tank meta).

I think this change would promote more dynamic gameplay and also make defensive gear more meaningful even at lower values with say a squishy rushing against an assassin or against a mage to minimize the burst damage they might take.

Thoughts? Comments?