@WyomingKnott, the idea is that when you purchase and setup this system, you plug in the mouse pad one time, and there after you never have to worry about plugging in, charging, replacing batteries, or the like, with the mouse ever again, so long as you remember to put it on the mouse pad. Most folks keep their mouse in roughly the same spot on the table near their monitor, regardless of it being wireless or not.
My question is whether the charger/mouse pad connects through AC outlet or USB. I'm assuming USB, so it can simply connect out the back of the PC (they do mention it has a USB pass-through). I would also expect the pad would provide the communication link between the PC and mouse, so that you don't need a separate unifying receiver. I've actually been talking to my brother about this for a few years now - why PC mice, which naturally pair with a pad that should be able to charge/power a relatively low-powered device, hadn't already been a thing. It's good to see wireless power tech pushing forward a little, but real penetration will come when this is an option at lower price points. It doesn't mention the cost of the charging mat, but the Razer version of this setup is apparently $250 - though it has RGBs in the mat too to help drive up its cost. If they can get the combined cost closer to $100 (which I believe is at least a couple years away) that is when wide-scale adoption will likely come about. For now, its something to think about for premium PC enthusiasts.