Another factor is that using vintage photographers and the lack of use by them of depth of field is slightly disingenuous. The early 20th century was dominated by either medium format cameras used to take in huge landscapes, or smaller cameras with lenses that would be considered very slow by modern standards. Where a modern lens has to be stopped down to at least 5.6 to 8 to start hitting the sweet spots for them, older lenses tended to have minimum apertures of at least 3.5 - 8.0, and would need to be stopped down even further (if stopping down was even possible) to get crisp results.
When shooting digital when you muff a wide aperture shot you can go whups and delete it on-camera. You didn't have that luxury with a Rollei or a press camera or whatever you would be using back then. Photography was far, far less forgiving to error, and playing with narrow depths of field is one of the most error-prone things you can do.
Another factor is the fact that prior to 1900, the fastest you would ever get would be f/8. Faster glass didn't exist. You didn't see lenses start creeping down towards f/2.8 or so until the 1930's, and these were expensive and rare and - as with all lenses - would need stopping down to get the best results from them. Again, no narrow DoF involved purely due to technological limitations.
Joe Hobbyist was probably running around with a Brownie or something at this point which was the early 20th century version of a 110 camera anyhow. Cheap, fixed aperture things designed to be sharp so they would sell.
It wasn't until the middle of the 20th century that TLRs and SLRs started to really come into their own and lenses would start getting fast enough that crazy-narrow depths of field would even start to become something you would even have to start thinking about in your composition process. Even then, the average hobbyist would be prone to avoid shooting that way because of the odds of blowing a shot.
You could argue that those f/1.2 - f/2.8 kinds of shots didn't become common until the last decade or two simply because technology now allows people to safely shoot at those settings and not have to worry about losing half a roll of film because they screwed up.
For fun, look at some vintage studio photos at some point - ones done in the 1800's into the 1900's. Take a good look at the backdrops. A sizable number would be softly painted landscapes. They aren't soft due to the background being blurred - they're painted that way on purpose. They were faking a narrow DoF because in-studio shots would be too sharp. A crisp backdrop would then be distracting to the subjects, so were made fuzzy on purpose.
EDIT: FWIW, I wasn't insulted or anything by the title. I disagree with your statement in it, but there wasn't any insult taken.