Well it's a very good point. I rang the other day for some prices for stuff like interior switches and a lot of them are discontinued 😢
Sorry to be the cloud to your silver lining . Hopefully soon they'll get picked up for specialist/classic car parts suppliers. But I'm not holding my breath
The specialists get their stock of genuine NOS parts by being available when manufacturers decide to devalue and dispose of it. Often this involves loading the stuff into the van, rather than paying a storeman to dump it all in a skip. This is a
very random process, and can result in the acquisition of stuff that you'll never sell. Anyone who ever went to RJ Grimes(Rootes/Chrysler etc) specialists will have seen this in action; for years there was a broken crate by the door full of new Talbot Samba headlights that must have numbered more than the remaining cars.
Don't forget there's a load of parts that they wouldn't have bothered keeping once production stopped as they usually outlasts the car and is never needed - there isn't, and never was, a complete stock of parts that you could build a new Omega from