You realise they can measure things like this anyway?
Not necessarily on an individual level, but on a regional/national level they can see when the load is high or low.
Or are you suggesting that they generate an individual tariff for every single household? which would be an absolute nightmare to administer...
Can you find me one tariff that allows them to charge you different rates by the hour, i cant find anything. Closest i can find is that economy 7 thing, but that two requires a different meter.