As someone on the “buy side” of Cloudflare-like services, that’s not how it works. How could a third party like Cloudflare protect my unprotected IP address? A very basic part of using a CDN/DDOS protection product is not allowing raw traffic to your origin server.

RE “as long as no one leaked their IP” - the IPv4 space is quite small. It’s trivial to scan it and discuss unadvertised, but ultimately very public, servers.

If customers don’t already have an understanding of both of these points, then they need to increase their competence in areas that are, frankly, pretty basic.