Now I hate Cloudflare with a passion, but even setting that aside, this is journalistic malpractice - it's basically a sponsored post. I was going to say I expected better from Ars Technica, but their glory days are long gone.
They literally are a DDoS mitigation service.
Source: me.
However in this case I think we can rely on them to tell us what they did. If they say they got a 7.3 Tbps UDP DDoS, chances are good they actually did.
What I say is that instead of hating on cloudflare one can look up how a DNS server works and start getting into DDOS mitigation ; but even after a couple of month anybody would still just have scratched the surface of it.
I don't think it's Cloudflare "goal" to centralize the internet, neither it is to set up captcha everywhere ; but it's definitely frustrating