Banks use tools as a store of value by holding some assets in reserves, for various economic benefits. Although, adopting Bitcoin in such capacity, would have it's pros and cons.
Let us say the banks are the governments because the Central Banks or the world banks is a Centralized sector controlled by the governments.
So haven put you expression to fact, YES the governments usually backs it economy system of the nation with resourceful assets that are potential to hedge against inflation over the long time to conserve economy values. The federal reserves had evolved around investing or holding on foreign bonds, global commodities and other global assets.
But as at the evolution of digital and economy financial system to Bitcoin development, adopting it for part of the reserve has become a more reliance to store values than those of the stabilized assets such as the US bonds that are negatively influenced by inflation and economy development.