The idea here is about security of money: the money stored in the CB ledger does not lose i ts contractual value in difficult times, as it is garanteed by the c

The idea here is about security of money: the money stored in the CB ledger does not lose i ts contractual value in difficult times, as it is garanteed by the central bank. Compare that to your money in your bank, which is backed at 10% with fiat reserves. If crisis happens and people want to pull their cash out the bank goes bankrupt. Central banks do not go bankrupt, hence your money is always safe.