If you have been a mechanic for 13 years I’m guessing you’re well versed on current components and work-arounds.
The tough part is the older stuff. I’m not in the industry, but I don’t see a good way forward trying to find old parts to do repairs.
As an example, someone brings in a high end 90’s mtb with quill stem, cantilever brakes, 1” steerer suspension fork that is shot.
John