"Monetary constraints only matter for countries that are not sovereign, e.g. the various members of the Euro area."
The members of the Eurozone taken together have the same sovereignty over monetary policy as any other country. But that's beside the point.
The point is that a sovereign country with a central bank can print its own money, but that doesn't mean it can borrow in its own currency. If that country keeps printing tons of money inflating away the value of its debt and running a current account deficit on top of it will not be able to borrow in its own currency under its own laws for long.
That's where monetary constraints become very real constraints, because the country loses its ability to import stuff it doesn't produce.
The members of the Eurozone taken together have the same sovereignty over monetary policy as any other country. But that's beside the point.
The point is that a sovereign country with a central bank can print its own money, but that doesn't mean it can borrow in its own currency. If that country keeps printing tons of money inflating away the value of its debt and running a current account deficit on top of it will not be able to borrow in its own currency under its own laws for long.
That's where monetary constraints become very real constraints, because the country loses its ability to import stuff it doesn't produce.