CK_beats
If you allow someone to fall back to insecure encryption methods this can allow them to exploit known vulnerabilities in these encryption algorithms. This is called a “Downgrade Attack”
Usually, when a provider is refusing TLS, it is not because they cannot provide TLS, but rather the person that is connecting to them has said in the TLS negotiation they only support algorithms that are insecure (according to the provider anyways). So when this occurs its best to check your TLS settings.