Self regulation is perhaps the wrong wording. At the heart of the crisis, were banks that were regulating a currency that wasn't their own, and could not be held accountable if it all failed.
I simply cannot imagine any reason why you might think that that is in any way a useful way to look at the problem. The financial crisis had nothing to do with the fact that banks were using US$. It's not even relevant to talk about that. If banks were using their own money they would not have been one penny more responsible. No conceivable aspect of bank issued money would in any manner have made the banks more responsible. In all seriousness the best possible scenario that can in any way be considered is that the banks would only have been a little worse rather than vastly worse.
it is just entirely outside the realm of imagination that what you were talking about could in any sense improve the situation. It's inconceivable. It's bizarre.
Why would I want to have to deal with lots of different potatoes available in one country with fluctuating degrees of quality and prices instead of the simplicity of just having one kind of potato?
On the more serious note, because the "simplicity" of one currency is simply more prone to systemic risks. Also, if there is free banking between multiple countries, it also has the advantages of having one currency as within the chains of supply, suppliers are not necessarily forced to switch currency.


