WIth Nuclear, Hydro, gas and coal you generate the amount of electricity that you expect the demand to be. The only time I ever had a problem with this type of power in Toronto is when a grid failure shut down the nuclear reactors and they had to do a cold restart. A once in a lifetime event. Rolling blackouts like what you mentioned often come from the lack of investment in generating supplies for the growth in usage (in addition to peak demand due to heat waves etc.). That type of blackout does not happen except when you have mismanagement in the grid or if you make it impossible to build new generating capacity.
When you talk about things like solar or wind -- your generation is not driven by demand.... you could have even a constant demand but if you have days without wind or a drop of 50%, or you need power at night when the sun goes down..... You still need generation capacity to fill that lack of power. People don't just cut back when the wind drops, they don't shut off all the lights at night..... they need a predictable amount of power. Solar and wind cannot produce that. You can build banks and banks of very expensive battery backup for when the grid fails (in my case locally it shuts off for 5 minutes every few days) if you are a company, but usually that is a stopgap measure that then for prolonged power outages switches over to gas generating backup generators (or some other fuel like that). This is the type of backup generating capacity for wind and solar - but no-one ever mentions it because it is a dirty little secret. They have mandates to buy power from home solar setups, they have to buy it whether there is a demand or not..... but there is no penalty if that same house which is on the grid fails to deliver power when people need it.... so there is a hidden subsidy of the grid supplier to buy backup power to supply both you and that house when the sun doesn't shine.