Yes, for example, pirate websites are often hiding their identity and if someone is infringing on your copyright you can't go and report it to their hosts because Cloudflare hides the IP. Reporting DMCA to Cloudflare won't give you the IP of their hosts.
A court ruling exempted Cloudflare from its users infringements of copyright making things easy for them.
In practice however, when you peel off Cloudflare you'll be stumped anyways as the DMCA request will be plainly ignored by those "bulletproof" hosts, so I don't think that knowing the real IP would change your chances, and if you're formally filing a case why just not subpoena Cloudflare?
A court ruling exempted Cloudflare from its users infringements of copyright making things easy for them.