It is not useless but it does have its price in terms of complexity and usability. With off peak at night you tend to run out of hot water during the day at times e.g. if you have visitors.
It is not a new idea and it is no panacea.
I've never seen it mentioned in any articles about baseline and peak power needs, and all that talk about grid batteries.
> and it is no panacea.
Nobody said it was. If it would, say, reduce the need for grid batteries by 10%, that would be an enormous savings. All by changing a new thermostat.
I remember in the 70s energy crisis the appearance of programmable thermostats what would automatically lower the temp at night. My proposal just extends that.