One thing to note here is that the Spanish government pushed heavily on favor of the interpretation that a region that splits from an EU member state also drops

One thing to note here is that the Spanish government pushed heavily on favor of the interpretation that a region that splits from an EU member state also drops out of the EU. This is a calculated move to create a disincentive. The flipside is that Spain was pushing for this when Scotland was holding its independence referendum. So the Scottish people were told that they would crash out of the EU if they voted for independence. Now they are forced to leave the EU because they voted against independence.