Why central bankers seems extremely stupid

Here is my point:

Let's ignore the fiat banker's capital owner, for the moment. Then here is a definition of a central banker:

Central bankers have the job of moving fiat to and from the economy, using actuarial losses and gains on their balance sheet.

Now Knut Wicksell noticed this some 200 years ago. Great, far out. He did get the sign wrong on low rates causing inflation, but otherwise he was right. He calls actuarial losses  a light breaking of Say's Law, according to Wiki.  Deliberately losing money, once in a while, is the central banker function.

Now fast forward to Ben's speech on deflation:

Of course, the U.S. government is not going to print money and distribute it willy-nilly (although as we will see later, there are practical policies that approximate this behavior).⁸ Normally, money is injected into the economy through asset purchases by the Federal Reserve. To stimulate aggregate spending when short-term interest rates have reached zero, the Fed must expand the scale of its asset purchases or, possibly, expand the menu of assets that it buys. Alternatively, the Fed could find other ways of injecting money into the system--for example, by making low-interest-rate loans to banks or cooperating with the fiscal authorities.

Why is Ben, 200 years after Wicksell, now discovering this basic principle of fiat banking? Why does Ben still have the sign wrong on rates and inflation? This is what bothers me, the simple basic steady state money flow equation is beyond their understanding.