Adding group SID's to an optional field in Kerberos was them using a standard to support their own system. It was never incompatible with MIT or Heimdal. Those

Adding group SID's to an optional field in Kerberos was them using a standard to support their own system. It was never incompatible with MIT or Heimdal. Those systems didn't use the group information in the optional field, but you could kinit and get a Kerberos ticket from a DC. I know I'm not going to change your mind, but Kerberos isn't a good example.