Roller bearings began replacing plain bearings 80 years ago in trains. This greatly reduced rolling resistance and improved reliability.
I remember when the local auto repairman was a blacksmith, machinist, and engineer. He worked on cars, farm equipment, lawn mowers, perhaps radios, and whatever else needed fixing. He could rebabbitt bearings without a trip into town for parts that might be unavailable. He could probably figure out what larger coil or flat springs a camera needed, and wind, machine, or forge them.
Today's "mechanics" have little experience in metal turning and milling, forging, brazing, welding, and engineering. They often rely on a computer instead of occasionally on a well-worn copy of Motor Manual for troubleshooting and repair. They may be certified in everything, but knowledgable in so little.
There are craftsmen who revel in the challange of problem solving and in fine worksmanship. This has been especially true in camera building and repair, where the repairman relies more on experience and intuition than on documentation. We see examples of this on APUG. Great craftsmanship, like great engtineering, is as much an art as music, literature, and the visual arts.
