Because everything we are is built on a house of cards.
Read this Article: Digital doomsday: the end of knowledge
Tom Simonite and Michael Le Page wrote:Yet even as we are acquiring ever more extraordinary knowledge, we are storing it in ever more fragile and ephemeral forms. If our civilisation runs into trouble, like all others before it, how much would survive?
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Whatever the cause, if the power was cut off to the banks of computers that now store much of humanity's knowledge, and people stopped looking after them and the buildings housing them, and factories ceased to churn out new chips and drives, how long would all our knowledge survive? How much would the survivors of such a disaster be able to retrieve decades or centuries hence?
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In 2008, for instance, it emerged that the US had "forgotten" how to make a secret ingredient of some nuclear warheads, dubbed Fogbank. Adequate records had not been kept and all the key personnel had retired or left the agency responsible. The fiasco ended up adding $69 million to the cost of a warhead refurbishment programme.
Something to keep in mind next time your AtB players/characters try booting up an old computer that's been gathering dust in the ruins on the Crash, or wonder why the few surviving humans didn't just rebuild the nuclear power plants and fast food joints.
Of course, since AtB is science fiction, anything is possible.