They destroyed it ostensibly so that they had a stronger guarantee that that GUID would never be generated again. That said, I suspect they understood it wasn't strictly necessary and were looking for an excuse to have some fun.
Note that even in the MAC-based generation algorithm, it is difficult (but not impossible) to accidentally generate the same one again even on the same hardware since there is a high resolution time component as well.
Random UUIDs have a different encoded version number so it's actually impossible for a modern one to collide with the one they generated.
