First of All, one of the reasons why I discuss here, and take AMD side, is because I hate fanboyism in any way shape or form, to counter typical "opinions" on forums. That is the reason why I hate SemiAccurate forum, because it is 95% red tinted all over it, and I hate Anandtech forum, because the most vocal users are Nvidia fanboys.
Secondly. I do not have RX 480, currently I use MBP mid 2012 with Geforce GTX 650M, and linux workstation with Xeon E3 and... Nvidia GTX 980.
Get the point what I am writing. Steam is not the whole world. Steam is used in richest countries. Nvidia sells the most cards in richest countries. And over 70% of RX 480 sales have been in other countries than the richest ones. Thats what have consumed the availability and rised up prices for AMD GPUs. I never think as simply as most people on this board do, I want to compare data from other points of view.
Fair enough about numbers. But it cannot be used then to draw any conclusions about whole situation about sales. If you are doing this, in any analysis, and take those numbers seriously, you should be fired from your work.
The whole world run mostly iGPUs as they don't have the mean to fork $300US on a video card when this is about or more than what they make in a month or year... dGPU are vastly used in the western developped world and Steam is one of the major gaming plateform in service today.