Actually that could have done well (although I wouldn’t hold my breath + all sorts of logistics of reality can prevent the utility). If you have 100 MWh of car batteries charging during off peak, that’s extra capacity you can leverage during peak hours.

I do agree that in practice that won’t work out for all sorts of reasons (the comms and standards for that aren’t defined afaik + what happens if enough cars disconnect that suddenly you don’t have enough capacity and brownouts begin to shed load)