Some comments from @sipa in #12702.

___

Yes, I think `importmulti` is superior in every way, except:
* Slightly less convenient to use (it requires redundant information, as you have to explicitly state what you want to import, and then give the keys/... to enable that).
* ~Doesn't support P2SH-P2WPKH yet~. Added in #14454

The latter can be fixed by just adding support for that case. The former can be improved by adding 'default' cases (e.g. if you prove a WIF private key, it can permit omitting the address, ...).

{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || (request.params.size() > 3 ))
        throw std::runtime_error(
            "getbalance ( \"(dummy)\" minconf include_watchonly )\n"
            "\nReturns the total available balance.\n"
            "The available balance is what the wallet considers currently spendable, and is\n"
            "thus affected by options which limit spendability such as -spendzeroconfchange.\n"
            "\nArguments:\n"
            "1. (dummy)           (string, optional) Remains for backward compatibility. Must be excluded or set to \"*\".\n"
            "2. minconf           (numeric, optional, default=0) Only include transactions confirmed at least this many times.\n"