Why can't AD champs have early Armor Pen that can be used late game?

Mages get Sorc Boots, so why is it that AD champions can't have any early armor pen? Brutalizer now only builds into Youmuu's Ghostblade, which isn't optimal on most champions who would build the Brutalizer, such as . All of those champions like early armor pen for one reason or another. And yet, the only way they can get that is , which can only be built into , which is pretty subpar on most of them, especially compared to the they like late game (save Kha'Zix).

This is a massive hit to their laning, in fact for some, especially Kha'Zix it makes laning practically impossible because you can't get early armor pen other than Brutalizer, which can only be put into Youmuu's or sold. So you either are stuck with Youmuu's or you have to sell the Brutalizer and end up wasting gold.

At least let Brutalizer have some sort of build path outside of Youmuu's and the jungle item. There's no reason for AD's to have to buy Brutalizer then sell it when Mages just get Sorc Shoes.