20-25kw is a normal size for a average home package. Once you add up all that could be on at one time, or if you heat with electric it can add up quick. There are homes in this country that have much larger units installed, depending live style based on needs or wants. The largest I've ever installed an commissioned was a 350KW Onan in a home in Miami Fla. It took all of it to run that home, pool heaters, atrium A/C units, elevators, kitchen, ect. My home unit is a 25KW I built from scratch, an many times while working in the shop it will peak at 23.5KW with the home running, plus a lathe, welder, planer, running at the same time. Many homes are used for work places, as well as entertainment. The last thing you need is for the power to go off an stop a project from being completed on time, or kill a business party. Then add the fact if the power goes off an you are away, you could lose everything in your freezers, or have the basement full of water, or busted plumbing do to freezing upon return. Many people see whole home backup power as a safety net, that does not require baby setting.
Once you know how a device, system, ect operates, finding the root cause in the event chain is easy. Until then, you will always be chasing/repairing the effects. Learning is a life time event, if you want to outsmart, whatever item you want to repair.