Ofc not. The person who sold you the car isn't responsible for the traffic. He is however responsible for the car he sold you and if it doesn't work, you are entitled to a refund. In this case, Blizzard is responsible for both the "car" and the "traffic." Simple as.
On the story itself, I'm extremely pleased about this. Not because I want bad things happen to Blizzard but it means consumer rights still mean something.