Looking back at the origins of the relativity revolution, it is interesting to note that the main reason given at the Saint-Louis conference of 24 September 1904 by Poincare for hesitating at a full endorsement of the principle of relativity was that celestial mechanics had suggested that the speed of the gravitational interaction exceeded that of light by at least six orders of magnitude (, p. 312, , p. 134; cit. in , pp.779-80).This is correct. Poincare was many years ahead of Einstein in relativistic analysis of gravitation and causality.
A few months later Poincare changed his mind, if tentatively, when he discovered what, in our terms, are the first Poincare-invariant formulations of gravitation. He announced and, respectively, described in detail these findings (among many others) in his two famous articles of 1905 and 1906 (, ). Historians of physics have often taxed Poincare with not being bold enough to espouse the new theory of relativity in the trenchant way adopted a few weeks later by a young patent office clerk, who nonchalantly disposed of the aether as “superfluous”.27
At an historical distance of more than a century Poincare’s hesitancy is worth our admiration for its methodological wisdom.
Yes, some authors are impressed by Einstein calling the aether superfluous, but he was just echoing what Poincare had been saying for many years. As early as 1889, Poincare predicted that “the day will doubtless come when the ether will be rejected as useless”. He repeated this in his widely-read 1902 book.
Capria has a lot of excellent detail on the history of special relativity in his 2011 paper. I had not seen this early, and it partially explains the bias against Poincare.