I dunno, nonce means number-used-once, it should be kinda obvious that it should be used only once?
Also, it's not entirely clear just how bad a reuse actually is. For example, in AES-CBC, reusing the IV has much less impact than reusing the nonce with AES-GCM.
Aside from just not understanding it, it's plausible that someone would generate nonces weakly, say, from a weak source of randomness.
Even using a strong source of randomness for an AES-GCM nonce is weak over enough messages, since it only gets you 48 bits of collision resistance.
If you're not using random nonces, maybe you want to use a counter, and then you have to worry about race conditions, state resets, etc. (if your system lost power immediately after using nonce n, would it boot back up and reuse it?)
This is actually generally fine for nonces (used in CTR and GCM modes, and in ChaCha20). Typically the only requirement for a nonce is that it is only used once. It is even safe to use a simple incrementing counter.
IVs, on the other hand, are required to be cryptographically random.