If you want to create balance in a game why would you add magic penetration boots (Sorcerer's Shoes) but not armor penetration boots. You allow mages to get the upper hand in damage earlier on but not AD's? Why not?
Armor penetration will help out many champions who struggle early game or don't do enough damage early game so why not balance the game and add it.
Armor Pen. boots + Brutalizer and you have all AD junglers and top laners doing true damage until late game.
And buff AD assassins? Please, just no. :P
For Marksmen, there are berserker greaves, which are much more effective than armor pen early on.
If you want to create balance in a game why would you add magic penetration boots (Sorcerer's Shoes) but not armor penetration boots.
Because balance =/= mirrors
First reason; AD champions already have AS or CDR as choices for offensive boots. If they're based on attacks, Berserker's Greaves covers their needs. If they're based on abilities, Ionian Boots will do. Or they can pick Swifts, Mobis, or pretty much any pair except Sorcerer's Shoes and still be effective (and tbh, sometimes they can get away with that because boots give minor boosts in the first place).
Second reason; adding more flat penetration causes more problems than it solves. If you have enough flat pen available to negate large enough portions of Armor, then you don't really need % penetration to deal with tanks (because, unless your entire team is physical damage, you can focus on the not-tanks while your magical allies can bust that tank open). You're able to get 50-100% Armor Pen against players who can't afford better Armor, so why bother with 35% on an inefficient item?
Pretty much what everyone else has said. There is a reason armor pen and magic pen items don't match up number per number. Armor pen is worth MORE in the long run. This is why as a midlaner, dualpen runes are actually significantly better on any midlaner that expects to attack with AA's more than 20% of the time. Armor pen is significantly stronger than spell pen. Spell pen is theoretically enabled by CD's entirely, whereas armor pen is enabled by AD and AS simultaneously.
Everyone starts the game with 15-20 Armor and 30MR.
Armor Pen Runes (19) + brutalizer (15) + 15 from Boots would be enough to deal true damage against level 10 targets.
Auto-attacks have very short CDs and are free. Unlike spells.
They would have to increase base armor and scaling at lower levels, effectively removing the entire point of having ArP Boots in the first place.
There are already enough easily accessible armor penetration and magic penetration in this game to negate almost all of a tank's defenses--even if their entire build is armor and health items to counter a carry/assassin/fighter or magic resist and health items to counter a mage.
Personally, I argue that Riot should remove or severely reduce armor penetration and magic penetration altogether so that counter-building with defensive items actually has a point.
You could make armorpen boots if you really wanted to. Here's what they would look like: Rofl AD Shoes: 1200 gold Stats: +5 Armor pen Passive: Unique- Enhanced movement: +45 movement speed
Anything stronger than that and you've got a serious balance issue
I think you're asking the wrong question. Rather than why we don't have armor penetration shoes, you should be asking why we have magic penetration ones. After the introduction of Ionian Boots, ability based champions can use the easy early CDR to increase the use of their abilities. WITHOUT turning into the Veigar that 1 shots Brand at level 6 because he has Sorc Shoes + Magic Penetration runes.
They could have them, I don't see why not. SMITE uses that set up for boots.
