User blog comment:Tridan V2/CCC2: Varion, The Warmourn/@comment-4068613-20140602003523/@comment-10768370-20140604084006

As I explained, runes and masteries do not give that high bonuses that can be influenced so it doesn't make that much of a difference. Items, on the other hand, give insanely high boosts when compared to runes and masteries. Furthermore, items are the choice of the player completely while masteries and runes are basically mandatory, there are only few players who do not have them and it would be unfair in my opinion to influence them. Here's a little calculation:

Masteries Armor:


 * Enchanted Armor = +5%
 * Hardiness = +5
 * Legendary Guardian = +20 (If the entire enemy team is around)
 * Total Masteries = 25 Armor +5% Armor

Runes Armor:


 * 9× Greater Mark of Armor = +8,2
 * 9× Greater Seal of Scaling Armor = +27
 * 9× Greater Glyph of Armor = +6,3
 * 3× Greater Quintessence of Scaling Armor = +20,5
 * Total Runes = 62 Armor

Item Armor:


 * 3× Thornmail = +300
 * 3× Frozen Heart = +300
 * Total Items = 600 Armor

Allied Champion Boost Armor:


 * Soraka's Astral Blessing = +110
 * Galio's Bulwark = +90
 * Mordekaiser's Creeping Death = +30
 * Orianna's Protect = +30
 * Total Boosts = 260 Armor

The Masteries+Runes can give significant bonuses, however they don't even come close to the items and/or boosts.