I was at first hesitant about mentioning this scenerio, but here is another twist on the parting out issue.
Let's say you're aimlessly tooling around and by chance you stumble upon a vintage bicycle. It immediately catches your eye because of the lugs, Nuovo Record Campagnolo gear, Brooks saddle, and such. Then upon closer examination the frame is either too large or too small for you to ride comfortably. The frame is pretty much a standard production model from the bike boom days. Rats; what do you do? Walk away and forget about it or maybe a light bulb goes off in your mind and....
YES ... on second thought you buy it and begin to explore the possibilities. I know a guy down the street who has been looking for a lightweight frame to hang some of his old racing day components on. Give him a call and he's good to go for the frame. Another friend has been searching for the Brooks saddle to complete his Paramount restoration. Call him and he is thrilled to have his pride and joy back to spec. Another friend; across town: has been looking for a 120mm flat QR high flanged hubset for tubulars with 36 spokes. You know he can't get to your house fast enough to pick them up and even brings his bike to try them on a short ride.
Already this bicycle is bringing great pleasure and enjoyment to the lightweight enthusiasts involved and will continue to do so for a long time down the road. One guy,who fit the frame,could have bought it and rode it as is. Or one guy could buy it and share the pleasure with several others.