As of 1919, the concept of long-distance telepathy was not new -- for it had been demonstrated and studied in England and Europe since about 1880.
The phenomenon was otherwise called "mental radio," and interest in it had caused a sensation reaching even into the United States -- where, by the way, the very idea outraged most American scientists and academic philosophers.
Even so, had not the Great War (World War I) intervened, it is quite possible that the history of developmental telepathy would have been considerably more progressive.
But the Great War did intervene, and all creative efforts of the Western world turned to dealing with its horrors.
And when the Great War was over in 1919, people wanted to forget the past which now seemed out-dated and begin history anew with fresh ideas not connected with it. Mental radio belongs to that past.
The concept of mental radio hung on here and there, especially as a science fiction topic.
But nothing was really done about it in terms of how to enhance and utilize it.
One major reason for this was that the concept of telepathy implied that some aspect of human brain could transcend the laws of physical space.
This implication conflicted with the dominant concepts of Western science. Those concepts did not permit transfer of information across distances except by physical means.
No physical sending-receiving equipment could be found in the human bio-anatomy or brain.