> That's just one mechanism, but not the primary way in which the Fed controls interest rates.
Yes.
> The Fed is a large provider of short-term loans ("fed funds") to cover interbank exchanges.
> It also is the lender of last resort and lends to banks directly ("discount rate").
> By changing these rates, the FED can influence the rates the banks charge each other for loans, and down the line to consumers.
And for those rates to take effect, the Fed still has to actually make (or receive) those loans at the announced rates. They don't just magically announce a rate, and then everyone charges that spontaneously.
So it's still about moving money in and out of circulation.
(Or at least the Fed needs to be ready to make and receive those loans, and anticipation does a lot of heavy lifting..)