The grandparent is basically right.
The Euro is flawed by design. Flow capitals works against the Euroarea. For instance:
The interest rate convenient for Germany is not the interest rate convenient for Spain. What do you think are the rates chosen by the Central European Bank? (clue: the ECB is in Frankfurt)
This shouldn't be more problem that the Fed rate affecting New York and Florida for instance, but there is not a common fiscal policy like in the States.
What happens is that capital in the banks of the north search bigger returns in hot economies (south countries) and create bubbles (Florida again?).
When the crisis arrive, we lend public money to (Greece for instance) so they can return the money to the (private) banks and, in a sleight of hand the fault is all of the lazy south Europeans.