Touchplate was a competitor with those old GE systems. They've been around a long time.
Go check out a new GE LV lighting control, and you'll see they use the same relays as they used then.
Touchplate has a ratcheting relay that advances on-off etc, each time it's given a signal from the momentary switch, so it only needs 2 wires to connect it.
The GE's need separate on and off signals from the switch, so require 3 wires.
