In NIST 800-90A, Hash_DRBG, HMAC_DRBG and CTR_DRBG (with derivation function) all require a nonce for instantiation.
I understand the usual application for a nonce to prevent replay attacks. However, I don't understand the security benefit a nonce provides for a CSPRNG. Additionally, I am wondering why CTR_DRBG without a derivation function does not require a nonce.
What am I missing here?