Can we be certain that there is a need to limit fiscal deficits in the euro zone?

Euro -zone countries must keep their fiscal deficit below 3% of GDP and have undertaken to reduce it to 0.5% of GDP in a few years. But is there a basis for these budgetary rules in the euro zone? The euro zone as a whole has an external surplus, and therefore excess savings and, accordingly, does not have to increase its public savings; One of the usual explanations for the euro zone’s budgetary rule is that fiscal deficits exert a negative externality on the other countries: it is argued that if a country has a large external deficit, this lead s to a rise in the euro zone’s common interest rate, which is negative for the other countries. But this explanation is not correct: if a country has a large external deficit, it is this country’s sovereign risk premium that rises, not the euro zone’s common risk-free interest rate; On the contrary, a large fiscal deficit in a country generates a positive externality on the other countries by stimulating its imports from the other countries, and therefore these other countries’ exports. The limit to fiscal deficits in euro-zone countries is perhaps only due to the fact that a country’s fiscal deficits must not be so high that they lead to a public debt crisis in the country, since the other countries then have to bail it out. But we are then talking about a higher limit than the one usually mentioned.