For your old appliances you still pay the same on average. A fixed price contract isn't cheaper, it just smooths prices into a long-term average. And many of the changes can be done manually. On your old dishwasher or washing machine you decide when they start, and most of them even already have buttons to start with a fixed-time delay. Instead of starting them at the end of day you can just start them when the wind is strong or the sun is shining, or watch the price feed. You even get to feel smart for saving money

I agree on the popularity, but you'd absolutely see an effect even without anyone buying new appliances