Completely agree. There a Jeep model that even has a second battery that most don't realize is there. When it dies it freaks people out because the battery shows as good, and it is. But the second somewhat hidden one is toast.Modern car’s computers don’t like to be without power for long, probably don’t like voltage spikes and often need to relearn idle settings and such so not a real good idea to try running without a battery in my opinion.
I was just trying to make sure people knew it could be done, because you don't always know when you'll need that info.
I've had a battery go too low to start a vehicle. Started another car, swapped batteries, and charged up the low battery. Not ideal, but it's handy in a pinch.