I am not telling anyone to GTFO, nor, I believe, Amazon does. It depends on a DDOS, there are a lot of smaller-scale DDOSes are just absorbed. Some are stupid filtered easy enough that no one is notified, some are serious enough. My first oncall at Amazon I got ddosed from 3 VPS machines, easy enough, a month after same attacker started to shift machines inside VPS, then a month after attacker started to spoof ips within narrow range of ips, in just a half a year (yes! they can last THAT long) attack was coming from a range of spoofed IPs with a traffic that followed no pattern except for destination they wanted to go down at many gigabits per second.
In this case - 700k QPS (gigabits of ingress) of well engineered HTTP/HTTPS DDOS traffic is not something an average colo can or even will be willing to handle at all. I'm assuming a hot-potato DDOS, when a customer comes along with a long tail of colos and providers that already booted him. All that traffic, servers and ultra expensive engineer time. Everyone wants it for free, but ALAS.
In this case - 700k QPS (gigabits of ingress) of well engineered HTTP/HTTPS DDOS traffic is not something an average colo can or even will be willing to handle at all. I'm assuming a hot-potato DDOS, when a customer comes along with a long tail of colos and providers that already booted him. All that traffic, servers and ultra expensive engineer time. Everyone wants it for free, but ALAS.