Hydrogen vs. Battery Electric Cars

Wait what is the argument about the grid again? The point was made that if all of California switched over to BEVs then the grid would fail so it would make sense to have fuel cell stations that would prevent all that stress going to the grid. But wouldn't most / all of that hydrogen be coming from electrolysis which is also taking electricity from the grid??? I feel like then the only grounds that argument has is that the electrolysis could just be done at times when the grid isn't stressed but that then just works in favor of the argument that we need more stationary energy storage and for that batteries work at a much higher efficiency. I think the only place where hydrogen makes sense would be for airplanes but the energy density of batteries is doubling every 10 years so the window of opportunity for even that is closing relatively fast. Feel free to correct me if I'm wrong. I'm not married to this perspective it's just my current understanding