Einstein seems to be so conveniently dismissive that he knew about the seminal Michelson-Morley experiments but he probably knew about it too well [1].

Einstein is not the first great scientist who are in denial of other important prior contributions, and he also not the last one. Newton also probably knew too well about Al-Haytham (Alhazen), arguably the father of modern science, and his breakthrough experiments but never directly cited Alhazen's works in his seminal books on Optics.

[1] Millikan, Einstein, and the Birth of Relativity (4 letters):

https://www.aps.org/archives/publications/apsnews/200403/let...

"Abraham Pais, who knew Einstein well and wrote his scientific biography, was certain that Einstein did know about Michelson's experiment before 1905. He points out that Einstein was over seventy and in poor health when he spoke to Shankland; at the first interview he probably did not remember that Michelson's experiment is discussed in Lorentz's 1895 monograph, the famous "Versuch", which Einstein had definitely read before 1905."

Was the ethical requirement to discuss and acknowledge predecessors work as developed in Newton's time as in our own? I would naturally expect not because it would seem to me to be the kind of thing that develops over time, but I could be wrong as I am not a historian of science.