I don't agree. I think you have to do what you can to make the recording of the song as good as possible. Some songs will sound better if there's noodley crap all over that can't be performed live, others will sound better if they're, in fact, recorded live. Don't restrict yourself or the artist in NOT recording some additional parts that come about in the process. That's probably more "artificial" than creating a recording that can't be duplicated live.
Having a record that can't be performed live is a problem, but that's the bands problem-- they're duty is to come up with a good show. You're duty is to make a great recording.