If I remember correctly, weren't the early ones at least more akin to this? I have a DK2 sitting in a box somewhere. Ordered it to mess around with and it was cheap enough that I could risk not getting a ton of use out of it.

I seem to remember that it was mostly done on the computer: IR emitters on the headset for tracking with a sensor/camera to receive the positional data to be processed by the computer. Then the generated output of the "camera" was sent to the display sitting behind the lenses.

There was definitely processing going on and you did need drivers/software. I'd imagine you could still use it with not much more than some lightweight drivers/software to process the positional data and render the appropriately distorted output.

You don't need the layers of bloatware on top of the sensors. Kinect for example just exposed and HID and library.