I wonder: if these are essentially just a “paper trail” for deposits made at the BoD by issuing banks, why bother with a physical banknote at all? In the case o

I wonder: if these are essentially just a “paper trail” for deposits made at the BoD by issuing banks, why bother with a physical banknote at all? In the case of an insolvency of a bank, the bank’s notes would still continue circulating, after all.