But wireless charging doesn't use beams. It's not radiowaves, it's a pulsing magnetic field, like in a transformer. It basically is a transformer, just with the two sides in different devices.
I could imagine you could create a grid of power transistors, that dynamically create virtual coils by shorting in a certain loop depending on the device above. But it would be very costly. But I don't think you can focus magnetic fields like beams as you can with radiowaves, especially in something that's supposed to be flat.
Also, with beamforming the transmitter origin position doesn't change, only the direction of the beam changes. But because the "receiver" would be right on top of the transmitter, it wouldn't really allow the receiver to change positions anyway, the signal doesn't travel far enough to really end up in a different place.