[senbrow]

Almost everyone is using these controllers wirelessly if I had to hazard a guess.

The USB interface is used for initial pairing and charging, in which case the port location doesn't matter nearly as much.

[jhasse]

Yes wirelessly via an USB dongle.

[yencabulator]

Steam Machine has a built-in antenna for Valve controllers.

[senbrow]

I'm pretty sure most PS controllers use Bluetooth natively if they're not connected via USB.