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, ...).

{
        already_witness = true;
        result = id;
        return true;
    }
    bool operator()(const WitnessV0ScriptHash& id)
    {
        already_witness = true;
        result = id;
        return true;
    }
    template<typename T>
    bool operator()(const T& dest) { return false; }
};
static UniValue addwitnessaddress(const JSONRPCRequest& request)