That's a lot easier said than done. The whole world operates on computers and the internet.
Loads of businesses suffered, but let's take airlines. What is the sensible alternative for flight reservations, scheduling, ticketing, boarding passes, baggage, etc? Just imagine the logistics involved in having a hard copy of everything needed for just a single flight, on the off chance that the computers go down - and there's 100,000 flights daily.
I guarantee that an airline would choose the alternative, risking a few days disruption once in a blue moon, to having a backup to all that.