With all the wires homerun to the panel, isn’t that actually MORE Copper?

The Copper cross-section of the Cat5 wires is much smaller than the Copper in 14/2 AWG AC wires. A typical AC wired home uses 2000ft of 14/2 (some builders still use 12 AWG for lights!) and about 60% is for lights and switches. That’s about 1200ft. Using LumenCache, you about double the total wire length, so 2400ft. That’s only 2.5 boxes of Cat5, which costs less than the 1200ft of Romex and that’s including the Cat5 connector cost.