It's an interesting balancing equation that someone could make an interesting game out of.
That gets you a few percent for the things that work like that, but most of the load on the power grid isn't able to do that. You can't turn off the heat in the winter, which is going to be an even larger proportion of the load in the future than it is now as we transition from fossil fuel heating systems to electric. People demand hot water. Refrigeration is a significant load but you turn it off and your food spoils.
Electrifying transportation is also a mixed blessing here. It helps smooth out the day/night load because you can charge them whenever generation exceeds demand, but after a couple days you can't put it off anymore and then you've just got more unsuppressible demand.
Isn't that the case?
Buffering systems can be effective for intra-day load shifting. You want to use electricity at noon and have heat at night. It doesn't work when you want to use electricity on Monday to have heat on Friday (tank would have to be too big and losses are too high) and it definitely doesn't work when you need heat on Monday but won't have the generation capacity until Friday.