The laws of supply and demand
To the person who ranted about supply and demand: you are in principle correct. However, it is the case that most small and medium consumers of electricity do *not* pay prices which fully represent the market cost of providing their electricity **at the time they use it**, not yet, not in any country I'm aware of. (The UK tried this approach in the *wholesale* market for a while, I do not now whether it still does follow this approach).
Anyway, most small and medium customers pay a fixed price per kilowatt hour. Big users already have "flexible pricing" where the price per kilowatt hour may vary with time, for example, electricity may be cheaper "off peak" than "on peak", which works well when big users are the largest part of the electricity demand. It has even been used with domestic supplies in the UK (eg the Economy 7 tariffs).
That model doesn't work so well if the largest part of the demand comes from people whose heavy electricity usage is *not* sensitive to the cost of providing electricity *at the time they want to use it*. The time they want to use it is important, because (a) electricity cannot sensibly be stored (b) sizing a power distribution network to cope with unlimited demands can be really very very expensive, which makes electricity even more expensive.
What market forces currently motivate the generating and distribution companies to keep the power supplies live at times of maximum demand? If it's easier+cheaper just to declare "emergency" when demand exceeds supply, and shut the network down, that's what they'll do (and that's what they've been doing in California, as I understand it).
This proposed move to test "smart load shedding" is an entirely understandable response to the market's inability to provide enough electricity metered and priced in an appropriate way.
If folk shut up and thought about it a bit, they might realise that completely shutting off *half* of California's air conditioning for (say) half an hour at a time, relying on thermal inertia to maintain coolness during that time, and then turning it on again for half an hour to make it stay cool, with 50% of premises "enabled" wrt aircon at any one time, just might save enough power for California to avoid grid and generator meltdown. Or it might not (there's some interesting sums to do).
The market could have chosen to motivate people to work their heavy loads (eg aircon) that way by increasing the standard price price per kwh of electricity and offering a discount to people willing to have selected high-demand appliances temporarily disconnected at times of peak demand (the "off peak" concept, except that peak time is no longer defined by the clock on the wall, but by actual real electricity demand). No government intervention needed. The market chooses not to do that, so someone needs to intervene to make something happen.
I'm not sure they've chosen the right something, if the reports are accurate, but there needs to be some mechanism for matching electricity demand to electricity supply, if the market isn't willing to invest in capacity and has no financial obligation to keep the supplies live.