Everytime I check this statement with Cloudflare-enabled sites... it was either always accessible (a nagging screen might be shown momentarily, but that's it), or the block is usually due to that site being a bank or something else that will block Tor users regardless of their firewall solutions. I've just tested it again just in case something has changed, but that statement holds up every time.
Can you please give a non-banking site that a) uses Cloudflare and b) blocks Tor?
Additionally, there are privacy reasons a person may wish to access a service directly and not be tracked by Cloudflare.
Cloudflare also has it's own onion service, sites can opt in, and Cloudflare's public DNS is also available over it, sidestepping the need to go over exit nodes after the first request.
In my own testing it wasn't too terrible to setup firewall rules and mutual TLS-based authentication of origin pulls, but it is certainly something where you have to do everything right to be as secure as you think you are. Versus just closing off inbound connections entirely and running cloudflared