True, but is in your hands. You can always have more fuel for your generator at the ready, larger batteries... you can have large amount of non-perishable goods at home. If you have a large garden, you can have vegetables and fruits that you can preserve. So technically, it is more of a question of how long do you want to be independent for,as it is entirely possible to be self-sufficient.
Even the German government suggests having non-perishable goods and water for about 2 weeks at home at any time in case of a prolonged emergency
Ja, of course. Point being that my friends have not considered the rest for becoming completely self-sufficient. They are very much into tech and less so in food preservation and gardening