You can still use older versions of sendmail.cf files but the best practice is to use the new version. The sendmail.cf file consists of settings and rewriting rules that get upgraded with every new version. Rebuilding the sendmail.cf file results in the tweaks being applied on top of the new settings and rules. Hence, it is recommended to use the new version of the sendmail.cf file.
For more details, see the following sources of information:
The /etc/mail/cf/README file provides a complete description of the configuration process
For information about the configuration file, see Versions of the Configuration File and sendmail Configuration File
For additional information, see Additional and Revised m4 Configuration Macros From Version 8.12 of sendmail