Existing grids have benefited from the fact that though any given individual demand rate might vary widely, averaged over a large number of consumers, trends are far more predictable.
On the generating side this hasn't typically been as much of an issue, with highly reliable and dispatchable generating plants. With intermittent renewable/sustainable sources, the fact that local variations in solar or wind capacity can be mitigate by transmitting surpluses, or importing necessary capacity, also helps. In an advanced grid with attached storage, again, large-number averaging should, with effective management, help balance supply and demand.
Trying to do this at the scale of individual households means far more variability which must be dealt with on he immediate premises. This is among the reasons I strongly doubt that visions of a "gridless future" will emerge, at least so long as there's not widespread collapse of all social and technical infrastructure.