The only active components in the schematic are a SATA signal conditioner, and a voltage regulator for that chip. I guess it's better to recondition the signal as soon as it comes off the cable as far as you can do; doing it the other side of the fake USB 3.0 port risks more corruption as the connector will be inherently a little bit lossy I guess. And given it's got power from the USB side, why not put a couple of low power components on it?
There are also a few capacitors acting as power buffers I guess, and that's it for the component count I think.