I actually looked into this, apparently its popular across western Europe (not just Germany) and a relic of historical times when the states didn't have centralized birth and death registries. I believe the limited validity and Apostille requirement is a medieval method to combat fraud.

As a new world Australian, the fact this remains in force is completely insane. In Australia the authorities can trivially query the birth and deaths register to verify the validity of certificates.

In Germanys defense, centralized registries were used by the Nazi regime to facilitate the Holocaust.

Anyway Biometric passports/ids pretty much completely supersede this use-case and can be as equally decentralized.