Yeah, but how many are in that good a condition? They are all 60-90 years old at this point.
If they weren't played much and stored in a cool place, they could be in excellent condition. Shellac is very durable.
Actually I have some records from the 1920s that were apparently unsold dealer stock, which are in near-mint condition. But although I’m no expert in these matters, I know how a lot of the surface noise comes from the bottom of the records’ grooves, as heavy needles dug into the shellac. There are people who re-master recordings utilizing things like needles which were made not to end in a ‘point.’ That tip is cut off. Leaving a needle that conveniently picks up the music from the ‘sides’ of the grooves, and avoiding the noise from the roughed-up bottom part.
There were also some cheaper dime-store records (labels like Grey Gull, Romeo, and such), which frankly, NEVER sounded all that crisp and clear. Even a ‘mint’ copy of these will serve up a pretty fair amount of surface noise. There was also the weird case of the “Diva” record label, which annoyingly stuck with ‘acoustic’ recordings for a good three or four years after the advent of electric recordings. They have great surfaces and play extremely well... but they all have a maddeningly dated ‘boxy’ sound of much older records, making them particularly exasperating.
They are actually relatively plentiful. Not available for 25¢ in antique stores, as 78’s were 50 years ago. A 78 that has been kept dry and cool, and unplayed, ages very well. On modern equipment, they will last hundreds of times longer than if played on machines from the 20’s or 30’s.