I think what you're trying to say is the CDN becomes another point of failure, that is, unless you have DNS failover which updates the DNS of cdn.example.com to point to your origin server's IP instead of the CDN in the event the CDN goes down. You should have monitoring & fail saves in place for your CDN, and if that's in place a CDN has higher redundancy vs just a single server is what the OP was trying to say, I bet.
