Why are the account rpc commands unsupported?

Now I can't set an address to an account .
./src/zcash-cli setaccount tmB3jNdeVJFgjNgUzmQHYhBKVU7PYisZytH hello
error: {"code":-11,"message":"Accounts are unsupported"}

Accounts have been deprecated in bitcoin core for several years. See: https://github.com/bitcoin/bitcoin/issues/3816

The basic idea is that the accounting system didn't relate to bitcoind's core task - to integrate with the bitcoin network.

Accounting (and other address/tx metadata) should be performed in application logic. For example, wallet software that interfaces with bitcoin/zcash core.

Previous releases of zcash retained that functionality of the older bitcoin source tree but it has since been dropped. Speaking for myself, I was glad to see it go.