So it is a compromised ethernet adapter. Nobody question the ability of Chinese spies to plant such a thing, but the "Big Hack" story implies that this is used as a mass infiltration tool, which I still find very improbable and lacks any evidence.
The way I interpret it is: since it's being introduced at the manufacturing plant, those installing the devices have no idea where the finished product will end up. Thus, these are not targetted attacks; they could wind up in the servers of a Fortune 500 company, or just as easily in some hobbyist's home lab. You'd need to compromise a large percentage of the products to increase the chances of landing a juicy target. The scattergun manner is what they're playing up here.
Considering that large scale internet companies like Amazon and Apple buy enormous amounts of hardware, it's not an insane strategy. If you compromise 1 of every 1,000 pieces of hardware (or even one of every 10,000) odds are you'll end up in a major datacenter pretty quickly.
