That being said, the line that catches my eye most is: "The fact the majority of smaller vendors were fine demonstrated that those having trouble had made mistakes." In my experience, that means one of two things:
1) The devs configuring the system didn't properly account for the sheer scale of the stress on their systems.
2) The smaller vendors took the change more seriously, and being smaller and more flexible, successfully updated their systems to interact properly with the new systems.
Or, of course, both.