Useful analysis from one of the linked articles, explaining why this is so dangerous:
Once an attack has been detected, the companies that CloudFlare buys bandwidth from—known as "Tier 2" providers—can then block the traffic to prevent it from entering their networks. That doesn't stop the problem, however; it just moves it upstream.
Tier 2 providers buy their bandwidth from the small number of Tier 1 providers. Tier 1 providers work a bit differently than Tier 2. They don't buy bandwidth from anyone. Instead, they just connect to other Tier 1 providers for free. These Tier 1 providers are the high-speed backbone that joins all the Tier 2 providers together, and hence makes the Internet a single global network, rather than a bunch of separate networks.
If a Tier 1 provider fails, that risks breaking the entire Internet.
Though the Tier 2 providers are blocking the flood traffic, the Tier 1 providers are still carrying it. As the DDoS attack has grown, so too has this load. The 300 Gb/s figure came from one of these Tier 1 providers. CloudFlare says that several of the Tier 1 networks have started to become congested, particularly in Europe. This congestion can make the entire Internet slower for everyone.
Scary shit.