Cloudflare is not the police. They're a private organization that makes a profit from offering "protection" for people getting DDoS attacked. They enable the people doing the DDoS attacks by protecting their booter sites (https://www.google.com/search?q=ddos+booter). That's called a racketeering operation (https://en.wikipedia.org/wiki/Racket_(crime)), and that's illegal. There are laws against it. Just because our crappy government is too incompetent to file charges doesn't mean it isn't illegal.
If Cloudflare thinks they can foster criminal activity through their network because they're running a juiced up nginx proxy, they're wrong. The "slippery slope" argument is absolute nonsense. As Krebs himself pointed out, they already remove sites that are hosting phishing attacks and malware.
Cloudflare, it's time to do the right thing here and stop protecting DDoS booters. Your policies are helping to damage the internet and censor people, whether they're illegal (they are) or not.