Why do people keep attributing these problems to Southwest's purchases of Airtran?

Airtran was successfully serving international destinations for years before Southwest purchased Airtran.

Southwest chose to abandon a functional system and create, from the ground up, a totally new system incorporating virtually no elements of the system they bought, including but not limited to routes, Air Crew (especially Captains), aircraft, software and trained airport personnel.

The problems with Southwest's international service are entirely of their own making and have no root in Airtran except to the extent Southwest has botched the integration of their purchase.