I don’t think this is quite true, although their maybe local politics that are making it true in certain areas.

Each of the demand response techniques you mentioned address a different concern, and are all complimentary to each other.

Planning and managing grid capacity happens on many different timescales. From decade long planning of large scale infrastructure, through to the millisecond-by-millisecond management that occurs during a grid crisis.

Each of the techniques you mention create a demand response effect at different timescales.

Simple multi-rate tariffs that offer different rates and different times of day, create macro scale changes in a grids daily demand curve. Reducing the peaks, and filling in the troughs, allowing distributors to reduce their total future CapEx spend.

Virtual power plants like Tesla allow distributors to “buy electricity” for cheaper than buying it from peaked plants for periods where they known that total demand is going high, and cheaper energy producers are already saturated. You’re operating on timescale looking a few hours or a few days into the future here. It’s important to note that Tesla themselves are creating addition value here, beyond simple tariff changes. Teslas virtual power plant will be committing themselves to a guaranteed load reduction at a specific period of time in the near future, failure to produce that reduction means Tesla has to buy extra electricity to make up the shortfall at extremely inflated rates. So Tesla create value through the efficient and accurate aggregation and management of many cars, dealing with issue like cars being unplugged, or already charged and varying levels of owner participation.

Electricity distributors requesting remote control is less effective than Tesla’s approach, because the distributor now has to carry all the risk associated with loads ignoring their commands. It’s basically impossible for them to mandate control, not unless their gonna employ the plug police to make sure nobody wires up a heater without telling them. Ultimately distributors can create and enforce load mandates by simple refusing to upgrade electrical connections to provide more supply, and downrating existing ones. This is already how industrial electricity supply works.

The number of types of demand response a specific load supports isn’t zero sum, it’s multiplicative. Each additional form of demand response supported creates additional value, and markets already exist to price that value.

In parts of the world with well functioning energy markets, the issues of how best to do demand response are handled by the energy markets. Each type of demand response (generally measured on two axis, speed of response and reliability of response) creates value for different market players. They can then create schemes to buy different types of demand response that fits their needs, or it can be bought though existing markets. The final piece of the puzzle is figuring out how properly aggregate individual loads into a large enough fleet that it can have a meaningful impact on the grid.

Unfortunately you changing the charging times on a Tesla has very little impact on the grid. But changing the charging time of 10,000 Tesla’s, now that might buy you a seat in the energy markets.