AFAIK because electricity is so essential, you can't cut off people's power without going through a lengthy process. You also can't cut off people's power during the winter, either.
So there's a form of it called "interruptible service", which is intended for things like water heaters. It lets the utility shed load during peak times, but it's part of the consumer rate plan so there are limits on how often and how long they can interrupt it for, etc.
There's also programs like OhmConnect (https://www.ohmconnect.com) where they just ask you nicely to stop using power under load, and maybe turn off your A/C, and pay you for it.
I gave up optimizing too much because my water heater forgets its temperature setting when you cut the power, and it's not like they paid me much anyway. Good thing I'm on the 100% renewable SVCE plan.
