The Armory and the new terminal shows they are moving way from loot boxes into a kind of "proof of work" economy, in which price is driven up by grinding and limited availability.

My personal theory is that it's related to their planned launch of their new VR headset soon, and want people to be able to buy it using the Steam Store - so deflating the market means there's reduced buying power on the market, reducing ways in which people can get money 'out' of Steam by buying hardware with Steam-bux and selling for real currency.