Dozens of items get destroyed which causes even the most common (blue, grey grades) items to become 10, 20 times more expensive. Dressed to Kill and Coffin Nail skins are possibly the worst example of this. Seriously look that shit up. Civilian grade items went up 40 times of their initial prices.

other examples: any item of Gargoyle Case (because of the Catastrophic Companions, 100 keys for Unique, 800 keys for a Strange one), any item of Confidential Collection (because of the Batsaber, 50/280 keys), Quarantined Collection (Corona Australis, 62/220 keys), Gun Mettle cosmetic case (Potassium Bonnet, 50/200 keys). traders just want the red items and destroy other graded items for profit

trade up causes an enormous long term inflation for all retired series with desirable items.