I don't think it's exactly the same thing as sssd is primarily a cache. You can use pam_krb5 on Linux too. But can you disconnect your FreeBSD laptop and work as normal from cache? I agree that sssd is quite finicky however, and I'd love a simpler alternative.

You are correct, sssd has a ton of features (like basically replicating the entire domain locally and caching passwords so you can roam away from your corp network). If you need those things, you need sssd.