And I'm thinking in a situation where you are on emergency backup power, you are not running all the lights, the electric pool heater, both ovens, and hosting a fondue party.
And there's the fact that genrac says the most sold sizes are 14-20kw.
I looked at my electricity usage over the last month. My max per day was 100 kWh. and that was with the pool pumps running 24/7 and running both ovens for the afternoon to cook weekly meals. And i'm in a 5500 sqft house with a pool. 2 x 3.5 ton ac units, Gas range, gas heat, gas dryer, gas water heater, and all LED bulbs, Radiant barrier, R20 walls. 4 of the people on my street have "whole home" generators and none are bigger than 20 kw.
Again, resistance Electric heat is dumb. But even in your situation , you could run one heater at a time on 30% of 200 amp service, which is 14 kw, which is what i said.