While macro financial tools and monetary policy may be sufficient to do that job most of the time, supervisory and regulatory policies have important economic and stability implications.
Particularly in a crisis, a central bank without knowledge of the way markets actually operate – knowledge that can gained only by experience and hands-on contact with banking organizations – will be, if you will excuse an ex-professor’s metaphor, at risk of failing its final exam. As a result, I think the separation of central banking and supervision and regulation is dangerous.