"Play on any SteamVR system. If you have VR hardware that works with a computer, then it works with SteamVR." Bravo Valve. This is why anyone interested in this should get a Vive and stay well clear of Oculus/Facebook's headsets. They are busy trying to capture the VR market by setting up exclusivity arrangements with studios to lock games to their platform to cut others out which just divides up the already small ma…
Although I suspect they have carefully made it so that the game has quite a few mechanics that would benefit greatly from the finger-tracking mechanics available only on the.... Valve Index. To be clear, your point is absolutely correct, but I'd be shellshocked if the experience isn't geared heavily to take the most advantage out of their own headset.
I thought Oculus touch did support finger tracking. Wikipedia describes it as a "system for detecting finger gestures which perhaps is different. I've only ever used a Vive, so I'm not sure.