Are you familiar with DDOS attacks? Current mitigation strategies are literally "have more bandwidth than they do" and null routing. Given that null routing effectively means people have accomplished their goal of bringing down a site, the only way to mitigate that is to not allow DDOSers to acquire enormous amounts of bandwidth.
It's true that a lot of the biggest issues would be mitigated if ISPs would consistently perform packet ingress filtering, fix open DNS resolvers, etc. But to act like this is an easy infrastructure problem is to ignore the technical challenges inherent in the problem.
It's true that a lot of the biggest issues would be mitigated if ISPs would consistently perform packet ingress filtering, fix open DNS resolvers, etc. But to act like this is an easy infrastructure problem is to ignore the technical challenges inherent in the problem.