Lets say for a moment that there was a situation that was caused by generation and not distribution, or an issue that was distribution at a main feed level. So we are talking about 100K homes. Average home feed is 100 AMP. Services are 200 AMP but total draw is at most 100 for the sake of math here. so 100K homes times 100 AMP is 10 Megawatt.
You left out the voltage in your power computation..
100 A * 240V = 24kW /household...
100k households is then 2400 MW.
There is an assumption, though, that not everyone draws full power at the same time. Typical practice in my neighborhood is that a 50-100kVA transformer feeds 6-8 houses, or about 10 kW/house. The local powerco engineer comments that we're a bit undersized. In the summer, there is definite light blink when the neighbor's AC starts up.