I'm pretty sure you missed his point entirely. They aren't running "another business" but instead finding some temporary storage place for the excess electricity. That's why the GP said "over supply utilization system".
Actually you're the one who missed my point entirely. My whole point was: storing energy (by melting salt or using any other kind of mechanism) is a process that needs an expensive plant. Running this kind of operation is not part of the power company's best interests. What the hell, even thermoelectric plants (the ones that generate the power being sold) are avoided entirely by this kind of company, who prefer to "outsource" the ownership and operation of these processes to a more competent enterprise.
You can't expect a wind-power-distribution company to start building giant thermoelectric/hydroelectric storage plants just for the sake of not wasting precious mother nature energy sources. It's just a business to them: if wasting energy by heating the nearby river costs less to them, that's what they'll do.
Most people simple don't know how much a plant with the sufficient capacity costs to build and run. Their operation needs to follow hundreds of safety, environmental and union regulatons, and the maintenance itself of the kilometers of tubes, cables and support infrastructure will cost (after 10 years) more than the initial implementation itself. And these plants need to run 24/7 because stopping and starting most processes is an energy-expensive (and cash-expensive too, and also maintenance-expensive, as the plant will degrade itself a little bit at every start-up process) operation.
That's why most thermoelectric plants run 24/7, even at periods (0-5AM) where the power wasted to the environment (through the boiler/tubing walls) is higher than the power being sold (at extremely low prices) to the consumers. They just can't stop their giant machine.
People love to propose lab benchtop solutions to giant infrastructure issues. Unfortunately, things are not that simple in real life.
Melting salt sucks up power and then generates it when you use that trapped heat to make steam later. Running pumps lets you store power with gravity. Pump water up higher, it releases the potential energy when it comes back down. And there are many other methods.
That's only possible if the government dictates the use of this kind of mechanism. Otherwise, the power company will simply do whatever they want to do, meaning "whatever costs less". Not wasting power is the concern of an individual, not of a profitable company.