It is possible that there are limits to the efficiency of the labour market’s ability to do that matching. Job search involves process lags, such as the window of time that an employer chooses to receive applications, as well as the decision lag involved in selection. So beyond some point, running the economy faster might not open the spigot that much wider.
For this reason, monetary policy is transmitted through a wide variety of channels, including one that we call the "interest rate channel". Through this channel, our interest rate increases impact the costs of borrowing. This makes it more expensive for households and enterprises to take out loans. As a result, their demand for loans falls.