That's not true. I work for a company that sells DDoS mitigation products to large network operators like Cogent for helping them deal with exactly these kinds of attacks in a much more sane manner than, "oy, just blackhole the destination and head out to lunch."

Either Cogent didn't buy our product (or a competitor's equivalent), or they have a network op who's a fresher and only knows how to blackhole things. Either way, it's a bad look for Cogent.