Okay, I can’t state this with absolute certainty, but I’d bet that in the past 70 a new, more economical and more easily printed negative has been made. Exactly when, I cannot say.
70 years
It isn’t about an easier negative. Different people want different qualities of light brought out in the print.
Burn one section of the photo, dodge another, etc. That is the hand of the artist.
If you make a copy negative off the print, the print is the original and everything else is a much less valuable COPY.
Also, in the computer analogy, you cannot use “undo”. If you mess up in a step, you start all over again (you cannot remove light exposure from a piece of photo paper under the negative).
Would you pay the same dollar to see Paul McCartney singing over taped tracks of the rest of the band “getting it perfect” in a studio that you would to see the whole band giving it a go, all at once, live?