EjustE

I suspect that you are talking about fixie/ss conversions by "butchered"... am I correct?

Blame the late Sheldon Brown for a lot of that. I do get the benefits of using a single speed bike, but one thing that I do not get (and for some reason it is not mentioned in many places and it is so darn obviously logical) is the fact that every one who has a bike with several gear he/she can ride it single speed, if he/she chooses to do so and if they want to ride it like a fixie (i.e. no coasting, they can do that, too.) Just lack of education out there

Now, if you refer to the practice of breaking a bike down to its single components and selling it, that's a different story and a lot of that has to do with supply and demand (and the cost of mailing full bikes). A lot of people who are restoring their own vintage bikes are looking for components. Unless someone is willing to disassemble a bike and sell the components separately, there would not be a source of vintage components....