>>276023370
Knuckles are the Index controllers. You have finger tracking.
Body tracking is kind of a hack that VRChat and a couple other games did using Vive tracker pucks. The pucks were designed to stick to props to make them trackable so that you could have an ecosystem of Wii-style cheap plastic controllers, but of course no one cares about that so probably 98% of sales are for VRChat users to track their legs while pole dancing. It seems like it's a good-enough solution for this one niche market segment that other companies aren't going to put much effort into unless it's cheap/free to implement, like some kind of camera-based tracking.