This is both speculative and dimly-remembered, but here's one theory.
One day in the 1950s my father brought home an album by German pianist
Fritz Schulz-Reichel performing as "Der schräge Otto" or "Crazy Otto".
He played ragtime on an out-of-tune piano.

He, in turn, might have done what I think a number of people did, which
was to try old ragtime rolls in old, out-of-tune player pianos without
knowing how to regulate the speed.

Matters improved around 1973 when Marvin Hamlisch scored the movie
"Paper Moon" with ragtime played as it was supposed to be played, and
Max Morath, a regular on Arthur Godfrey's very popular radio show (it
lasted into the 1970's) played a good deal of ragtime there.

Mark Kinsler

 [ Ref. https://www.youtube.com/watch?v=HDzLLYLzmVM 
 [ and https://www.youtube.com/watch?v=SgDj7zWhpeU 
 [ My theory: the out-of-tune piano was a 1950s sales gimmick by
 [ "Professor" Lou Busch (performing as Joe "Fingers" Carr) which
 [ Schulz-Reichel copied in 1953.  Both pianists undoubtedly
 [ suffered out-of-tune pianos over the years.  -- Robbie