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.
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.