While most of the additional functionality the old account system had over the label system were irrelevant, there is one critical functionality that no longer seems to be possible with labels - specifically, the ability to request a list of transactions (TXID + amount) that pay to addresses with a given account/label. As per the release notes for 0.17.0. the _listtransaction_ method was changed as follows;

> The account named parameter has been renamed to dummy. If provided, the dummy parameter must be set to the string *, unless running with the -deprecatedrpc=accounts argument (in which case functionality is unchanged).

_getreceivedbylabel_ and _getreceivedbyaddress_ only returns the balance, while _listreceivedbylabel_ and _listreceivedbyaddress_ do not actually filter; additionally, the former does not list transactions at all, while the latter does not include the amounts per TXID. While you could use _getaddressesbylabel_ to iterate over addresses, there is no corresponding method to get the TXIDs and amounts from this list of addresses. None of these can therefore be used as a direct replacement for this method.

The only way I can see to get anything resembling the old functionality with the API changes is to dump the entire transaction history with _listreceivedbyaddress_, filter the result by label manually, then use _gettransaction_ on each listed TXID. This is both very fiddly and very inefficient, and likely impossible when you go past a certain number of lifetime transactions.

Am I missing something here, or will it really no longer possible be to iterate over transactions received by account/label? If so, this basically means that many applications will no longer be usable with releases starting from Bitcoin Core 0.18.
"      \"maximumAmount\"    (numeric or string, default=unlimited) Maximum value of each UTXO in " + CURRENCY_UNIT + "\n"
            "      \"maximumCount\"     (numeric or string, default=unlimited) Maximum number of UTXOs\n"
            "      \"minimumSumAmount\" (numeric or string, default=unlimited) Minimum sum value of all UTXOs in " + CURRENCY_UNIT + "\n"
            "    }\n"
            "\nResult\n"
            "[                   (array of json object)\n"
            "  {\n"
            "    \"txid\" : \"txid\",          (string) the transaction id \n"
            "    \"vout\" : n,               (numeric) the vout value\n"
            "    \"address\" : \"address\",    (string) the bitcoin address\n"
            "    \"label\" : \"label\",        (string) The associated label, or \"\" for the default label\n"
            "    \"scriptPubKey\" : \"key\",   (string) the script key\n"
            "    \"amount\" : x.xxx,         (numeric) the transaction output amount in " + CURRENCY_UNIT + "\n"
            "    \"confirmations\" : n,      (numeric) The number of confirmations\n"
            "    \"redeemScript\" : n        (string) The redeemScript if scriptPubKey is P2SH\n"
            "    \"spendable\" : xxx,        (bool) Whether we have the private keys to spend this output\n"
            "    \"solvable\" : xxx,         (bool) Whether we know how to spend this output, ignoring the lack of keys\n"
            "    \"safe\" : xxx              (bool) Whether this output is considered safe to spend. Unconfirmed transactions\n"
            "                              from outside keys and unconfirmed replacement transactions are considered unsafe\n"
            "                              and are not eligible for spending by fundrawtransaction and sendtoaddress.\n"
            "  }\n"
            "  ,...\n"
            "]\n"
            "\nExamples\n"
            + HelpExampleCli("listunspent", "")
            + HelpExampleCli("listunspent", "6 9999999 \"[\\\"1PGFqEzfmQch1gKD3ra4k18PNj3tTUUSqg\\\",\\\"1LtvqCaApEdUGFkpKMM4MstjcaL4dKg8SP\\\"]\"")
            + HelpExampleRpc("listunspent", "6, 9999999 \"[\\\"1PGFqEzfmQch1gKD3ra4k18PNj3tTUUSqg\\\",\\\"1LtvqCaApEdUGFkpKMM4MstjcaL4dKg8SP\\\"]\"")
            + HelpExampleCli("listunspent", "6 9999999 '[]' true '{ \"minimumAmount\": 0.005 }'")
            + HelpExampleRpc("listunspent", "6, 9999999, [] , true, { \"minimumAmount\": 0.005 } ")
        );