BUT... the moment the bank suffered a loss or a borrower stopped paying interest, *everybody* would know and a run would surely start within moments.
Banks always lend a sizeable chunk of their own money alongside depositors. As long as that buffer isn't running out, there's not rational reason for a depositor to worry. It would take a lot of losses to trigger a bank run (like we saw in 2008). Knowing the exact amount held by a bank would also protect against bank runs being started on just a rumour, and it would encourage banks to keep and prove they have a large reserve, so that the depositors are reassured.
Agree that false rumours would be harder to spread and I also agree transparency would lead to greater conservatism.
However, it would be fascinating to see how things played out in the real world. For example, banks today only need to publish their accounts periodically (e.g. quarterly) and go to great lengths to make them look good (e.g. the Lehman Repo 105 transactions, the tendency of companies to discount heavily towards the end of a period to get signings, etc, etc).
In between reporting periods, I suspect the numbers jump all over the place.... and the same would be true here.... even if a "Bitcoin bank" were very well run, well capitalised and had lots of liquidity, there would be periods where good borrowers were a bit late and some depositors had drawn out more than expected - and a snapshot at that time would make it look like it was about to collapse.
Perhaps the solution would be even greater transparency - e.g. the successful banks would also make their internal models and cash-flow forecasts public - and reconciled against the blockchain. One thing's for certain, I don't think a bank based on obfuscation/secrecy would stand a chance.
Also nothing stops the existence of a "lender of last resort". The difference is that unlike the Fed, it can't just print on demand, so it'd have to hold large amounts of cash to be sent to a distressed bank at a moment's notice. That would be pretty expensive.
Agreed. So, in many ways, it would be similar to the gold standard days (e.g. the JP Morgan stories from the 1907 panic, etc).
And I guess you could be sure there would never be anything as scary as this
http://soberlook.com/2013/06/how-did-we-get-here-map-feds-balance.html