It would be fair to say that those caused the 2001 default. Which was a real default, but not a catastrophe; defaults happen sometimes, Argentina negotiated a settlement with (most of) its creditors (who had known all along that their investments carried a certain risk), and life went on.
What we have now is a tragedy where the overwhelming majority of Argentina's creditors were reasonable, accepted the settlement, and want to get paid, and Argentina has the money and wants to pay them. But the "vultures" are using a legal technicality to stop that payment from going through, in the hopes of extorting more money from Argentina. And sadly the US legal system is abetting this.