This is a bad explanation so someone should word it better.

A DDOS attack doesnt have to target SE servers specifically but can be against any link in the chain of connection to SE. SE cant do anything about ISPs being over loaded elsewhere that interupt their service. And tandom DDOS are common by botnets since they are most likely trying to packer flood so someone/some group can access information from companies, things kike billing, payment information etc.

It rarely has anything to do WoW some angry nerd.