[robinson-wall]

It's still possible to design a badge system on an independent network (think just switched within a building) which syncs a local copy of the authoritative ldap from the corp domain, so your badge readers stay working if the link to the corp domain goes away.

It's just more expensive and another thing to maintain, and still doesn't account for _all_ failure modes (what if you sync really frequently and a bad change was made deleting all accounts?)