I have no idea, sorry. It would be very interesting if it were true, but it sounds like a bit of an urban legend. Working within the constraints of limited resources seemed to be a constant in all of Japan's pre-bubble successes, from comics, to calculators, so I wouldn't assume there would be any extraordinary reason for early Japanese animators to follow the same principles.
My interpretation was that anime's more limited, stylized animation was due to its direct influence from the prolific manga artist and animator Osamu Tezuka (sometimes called "the Walt Disney of Japan.") All comics, Western or Eastern, must heavily stylize motion in order to have any hope of expressing it in still frames. So having an accomplished dramatic comic artist lead most of the earliest, most influential Japanese animations, most of which were direct adaptations of his comics, working with the low framerate stylized motions that extended naturally from comic book stills, seems to have had a profound effect on the Japanese school.
In contrast, Disney's early animations were inspired by conventional cartooning in subject, and early film and Vaudeville in motion, so given Disney's influence, it should similarly not be surprising that the Western animation school tended towards comedy and fluid motion that attempted to emulate the impression of film.
My interpretation was that anime's more limited, stylized animation was due to its direct influence from the prolific manga artist and animator Osamu Tezuka (sometimes called "the Walt Disney of Japan.") All comics, Western or Eastern, must heavily stylize motion in order to have any hope of expressing it in still frames. So having an accomplished dramatic comic artist lead most of the earliest, most influential Japanese animations, most of which were direct adaptations of his comics, working with the low framerate stylized motions that extended naturally from comic book stills, seems to have had a profound effect on the Japanese school.
In contrast, Disney's early animations were inspired by conventional cartooning in subject, and early film and Vaudeville in motion, so given Disney's influence, it should similarly not be surprising that the Western animation school tended towards comedy and fluid motion that attempted to emulate the impression of film.