Until recently, I might have (wrongly) asked someone, “Do you use Kerberos or Active Directory?” They are now the same thing.
Kerberos is everywhere (now). As recently as May 2022 even Azure AD now uses it as the primary authentication engine. Kerberos has been the main authentication engine for many significant things for more than a decade, like PAM, which is the main authentication engine for SSH itself.
Learning how Kerberos works, and how to maintain it, is an essential skill for any experienced infrastructure engineer (or hacker). Therefore, a full Kerberos setup should be a mandatory part of any enterprise home lab.