There are many reasons Cloudflare should be hated. The main one is that their goal is to centralize the Internet. A secondary one is all those bloody captchas. A tertiary one is that they often block Tor, even if you pass a captcha. Yes, it's configurable, but their recommended settings are the ones that help break the internet. A fourth one is that many DDoS-for-hire sites are protected behind Cloudflare, which allows them because they are good for its business model. Need I go on?

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.