The tricky part is not much "power production" but "keeping the grid at a certain frequency" witch means balanced between consumers and producers.
A classic large-enough but not too large grid is sized like that to achieve a somewhat constant load so their generator have to supply a certain amount of power without sudden high or low loads spike. A small personal example, I have a small domestic p.v. system for self-consumption, when my dishwasher start heating water my micro-grid load suddenly spike +~2kW my inverter take time to produce more, like few seconds, so without a grid or a battery my micro-grid will simply collapse because the frequency goes too low. Similarly when water heating phase is ended there is a sudden -~2kW load and the micro-grid frequency skyrocket. Again without a grid or a battery my micro-grid will simply collapse due to a too high frequency.
Instead a small sudden load change, like a light that turn on or off, have essentially no impact since such so small amount of power vary the frequency of the micro-grid so little that the solar inverter have no issue to keep anything in place.
At a classic grid scale ±2kW are just background noise on the frequency, like for my microgrid the led light turned on and off.
However at a classic grid scale with massive p.v. things start to be far less constant, sudden spike for so many microgrids means sudden spikes projected to the main grid causing much more frequency perturbations. Also Sun power tend to peak really fast witch means that a grid with an actual production of let's say 1GW at 10 a.m. this morning around my latitude suffer a sudden drop in demand, witch means a high frequency peak because that when most p.v. systems in sunny days quickly goes from few hundreds W to few thousands W in a very little time. So the grid need to reduce power quickly, let's say a quick perturbation pass varying much the p.v. production, again a load peak for them, a big drop in frequency they need to boost production in very few seconds to keep up the frequency. The alternative is rolling blackouts to cut most perturbation and keep the overall grid up, something that do not touch much those how have a p.v. system with battery storage since actual inverters are fast enough to keep homes powered on most load cases BUT touch all other citizens...
grid-connected EVs can help quickly absorbing loads and quickly releasing energy BUT for far such applications are just on paper and I doubt we can allow private EVs to talk with the public grid since any vehicle is a mass of proprietary crapware crap built by countless of private parties, many outside national Govs. control, in unknown health shapes, response time, ... such grid is theoretically possible, but practically probably as unstable as without such system, with many smaller rolling blackouts and much higher risks of large scale ones...
Long story short:
- with climate change we know we have to adapt and adapt means change, changes we can't much design up front due to too many variables, witch means we can't build large/complex systems because they solve a PRESENT issue, taking years to be built, and we do not know if such issue will be solved in the same way once we finished such large systems.
- the ideas some from Green New Deal push is: we need to cut such complexity. Witch means making autonomous homes who can be powered locally without a grid, smaller cities with their own local small networks etc instead of nation-wide systems. The very same happen for transportation networks where we start preferring small/medium water and air born systems because we can re-organize them fast instead of rails and roads that take decades to be build and changed.
- the issue here is that PERHAPS we can do so, but very unlikely for anyone, probably only of less than a third of the whole humanity and of course those who are excluded for a reason or another would not be happy of that, and not "being happy" means unrest, revolutions, violence, instability etc that beside the carnage and suffering also impede to build pretty anything for anyone.
Energy grids operators are just some of the party who start understanding the amplitude of such issue and start blowing all whistle they have alerting: "we can't do that, we do not know alternatives to put on the table".
Probably the sole viable alternative we have is PUBLIC only nuclear waiting for tech progress, but so far build such massive nuclear move takes decades.