It's a quirk of the Qualcomm chipset they used in the Quest. It has an extra DSP accelerator that was originally unused, but they managed to repurpose it for hand tracking. It was an opportunistic play, as I understand it.
Could you link to a source about that dsp being specifically used for hand-tracking? My quick google didn't found a result that could confirm that and it would explain a bit. Thank you!
It's in here somewhere. It's also extensively covered in the hour breakout session by the folks who implemented it, which is uploaded somewhere though I can't find the link atm.
