zebrad supports a subset of the zcashd RPC commands. This subset is currently increasing as we work towards zcashd deprecation. So I don’t think this in particular is a problem.
We do have to improve documentation. All of the existing documentation (Zcash 6.1.0 RPC Docs, zcashd internal help, and zebrad’s OpenAPI specs) is outdated in some manner. We should streamline and updated it (like I mentioned, my suggestion would be to update the Zebra docs and update the tool that generates the OpenAPI specs from these docs)