So when I expressed surprise to the Minister who was responsible for the Reserve Bank legislation that the Bill envisaged the Policy Targets Agreement being between the Minister and the Governor, not between the Minister and the Bank, he explained nonchalantly that "We can't fire the whole Bank. Realistically, we can't even fire the whole Board. But we sure as hell can fire you!"
So leaving the Governor in sole charge of monetary policy decisions makes it very clear who is to blame if inflation falls outside the agreed target. Having a single decision-maker also makes communicating the Bank's monetary policy message relatively easy also.