Huh. Who'd a thunk it.
made possible by the nearly universal distribution in recent years of residential smart meters
This is key. Demand-based metering and pricing has been available for industrial customers for a long time but residential customers had dumb mechanical meters that only recorded total kilowatt-hours. This sort of thing will also become important as electric cars become more mainstream, to encourage people to charge cars at low-demand times. Otherwise everyone plugging in their car at 6pm when they get home from work, while also cooking dinner and turning on the A/C is going to stress the grid.