Could you imagine if ap magees had access to that much magic pen

10 from runes 10 from mastery and 15 from boots and the last but not least liandrys. you forget that ad doesnt get pent from boots so before you complain

could you imagine if tanks had as many mr options as they did armor options

could you imagine if ranged champs DIDN'T have 30 flat MR for the entire game unless they specifically buy MR items or put it in their runes????

armor scales with level, MR doesn't. Also you can get 30 magic pen from items, and an always there 35%. AD can get 45 from items that scales up (55 if you buy a serrated dirk too for some reason), 45% for bonus armor, and 30% if they can get 6 stacks from black cleaver.

Because MR isn't found in as much quantities as armor.

There's 16 fully built armor items compared to 14 fully built MR items.

There are 3 items that have both stats and note that all 3 of them provide no HP and two of them gives less MR than than the armor component.

5 MR items give less than 40 MR. No MR item goes above 70.

3 armor items give less than 40 armor. Two armor items that go above 70.

Max base MR at 18 is 53.4. This applies to nearly all melee champions. Minimum armor value at 18 is 68 with Orianna if you don't counter mini Gnar and Thresh.

Nearly all magic damage are from spells.

AP casters rely on their spells alone to deal damage. AD casters rely on their spells and auto attacks to deal damage. AD is superior to AP if no resistances were in the game.