It is also worth noting that CDKeys buys most of their keys from retail outlets where the cost of the game is much cheaper to reflect the strength of their regional currency. This means that the pot is split up even more than a Steam direct purchase. I think the breakdown is retailer, CDKeys and Bethesda (maybe even Steam for key generation), as opposed to just Steam and Bethesda.
No developer or publisher sees a cent from a resold key. It's the digital equivalent of buying used.