The truth is that neither these ppl nor anyone else at the time thought that Einstein had any significance advance over Lorentz and Poincare.
Lorentz was generous to Einstein (and to FitzGerald, Voigt, and others), but he credited Poincare more. A I noted:
Lorentz published his 1906 Columbia U. lectures on relativity, where he described Einstein's work without expressing any disagreement with it. That is where Lorentz says, "Einstein simply postulates what we have deduced". After praising Einstein's simplicity, he says, "Yet, I think, something may also be claimed in favor of the form in which I have presented the theory." Lorentz was saying that he and Einstein had different ways of presenting the same theory, with advantages and disadvantages to each approach.Walter Kaufmann wrote something similar in 1906.
This is exactly correct, as I explain here. The core of Einstein's 1905 paper was to give an exposition of Lorentz theory, with the main simplification being postulating what Lorentz (and Poincare) proved.
Bucherer wrote a 1908 paper on The Experimental Confirmation of the Lorentz-Einstein Theory. His mild credit for Einstein is "The relativity principle is clearly emphasized in Einstein's version."
In crediting for the Lorentz transformations, Lorentz wrote:
These were the considerations published by me in 1904 which gave place to Poincaré to write his paper on the dynamics of the electron, in which he attached my name to the transformation to which I will come to speak. I must notice on this subject that the same transformation was already present in an article of Mr. Voigt published in 1887, and that I did not draw from this artifice all the possible parts. Indeed, for some of the physical quantities which enter the formulas, I did not indicate the transformation which suits best. That was done by Poincaré and then by Mr. Einstein and Minkowski.Einstein gave only limited credit, as he spent his whole life trying to cheat ppl out of credit for their work.
Minkowski is not much better, as noted here, but at least he credited Lorentz and Poincare more than Einstein.
Perhaps Max Born found relativity easier if the relativity principle is postulated, instead of deduced from Michelson-Morley. Or maybe Born just liked Einstein better, as they were life-long friends. But he never explained how Einstein's work was any better than that of Lorentz and Poincare.