Even worse when a generator goes out (or is destroyed). It can take months to get a new one. Hope we don't have multiple generators go out at once. They're not just sitting on a shelf somewhere waiting to be picked up.
One of the biggest issues is that traditional resources (coal, nuclear, gas) can run for long periods of time and in many places have a pretty reliable fuel supply. Renewables are great, but you could be generating lots of power one minute and then it's all gone the next hour. This causes a lot of stress on traditional resources which need to be ready to counteract this. Coal plants and gas plants were never designed for that either and it's causing issues.