“Why? Because demand has to be there if all 7500 people turn on their AC at the same time while they’re cooking, etc. “
I should my math. Many more than 7,500. Show your math.
For example, with my home solar I have to consider not just the total solar in kWh collected and stored into batteries during the day, and how much total kWh in power my home needs throughout the day, but also how much I need at any one time. If I had enough inverter capacity to provide just 10kW of continuous AC power, then when we get home with the EV and charge it at 9.5kW, I'd have just half a kW of capacity to run the rest of the house. Even if my 20kW of solar panels was easily keeping my 92kWh of battery storage full, if I can get only 10kW of AC at a time I would have to pull from the grid a lot if I ran some of my appliances while I was charging the EV while my electric furnace was on. For that reason, I realized it was worth spending a little extra to increase my inverter capacity to meet the demand my electrical panels often need. Even if my inverters don't have to produce that kW demand all day, when I need it I need it.
That's why I say that you're right to make the averages part of the equation, but respectfully I say you're wrong to just discard demand.