The reverse is also supposed to be true. Even shifts of a quarter of a percentage point are sufficient to send the stock exchanges tumbling together with the bond markets. In 1994 a long term trend of increase in interest rate commenced in the USA, doubling interest rates from 3 to 6 percent. USD in 1 year. Even today, currency traders all around the world dread the decisions of the Bundesbank and sit with their eyes glued to the trading screen on days in which announcements are expected.
Interest rates is only the latest fad.
Otherwise, they would restrict the amount of printed money and limit the government's ability to borrow. Even prior to that fashion there was a widespread belief in the effectiveness of manipulating exchange rates. This was especially true where exchange controls were still being implemented and the currency was not fully convertible. Britain removed its exchange controls only as late as 1979. Free flows of currencies are a relatively new thing and their long absence reflects this wide held superstition of central banks.