We aren't talking about installing a single light that we pump all of the world's energy into, making it ever brighter as we drive the cost/benefit further and

We aren't talking about installing a single light that we pump all of the world's energy into, making it ever brighter as we drive the cost/benefit further and further into the realm of diminishing returns. We are talking about scaling a few common "good enough for X activity" lighting setups across billions of installations, and that process is very linear.