The real quote is, Eine neue wissenschaftliche Wahrheit pflegt sich nicht in der Weise durchzusetzen, daß ihre Gegner überzeugt werden und sich als belehrt erklären, sondern vielmehr dadurch, daß ihre Gegner allmählich aussterben und daß die heranwachsende Generation von vornherein mit der Wahrheit vertraut gemacht ist. which is better translated as A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it. This was cited in Kuhn's famous book, _The Structure of Scientific Revolutions_ which explains why it is so.
"...one funeral at a time" is a pithy condensation of what Max Planck actually did say.
Einstein, who you mentioned, is the quintessential example that science progresses one funeral at a time. He was a brilliant scientist who not only single handedly ushered in one of the two pillars of modern physics but sparked a revolution in the other. His own research into the photoelectric effect was one of the earliest hard data that showed that quantum phenomena were not deterministic and yet he fought against the very concept of nondeterminism for decades. He went so far as to popularize the quote "God does not play dice with the universe" and despite a wealth of experiments or effective theories to explain them, he continually rejected the Heisenberg uncertainty principle. Even though he still contributed a lot to physics and remained friendly with the rest of the theoretical physics community during that time, he was essentially a social pariah when it came to his thoughts on quantum mechanics. However, he was already a very public and popular figure (think Neil Degrasse Tyson minus the ubiquitous television) so this very very wrong belief led to an untold number of rejected grants and misguided careers.
On what personal knowledge do you disagree with the conclusions of scientists and historians of science?
I already pointed you to the actual quote. And a book to look into. I can give you no shortage of examples. For example for famous examples of scientists in the 20th century that rejected new scientific theories, I can offer Fred Hoyle's refusal to accept the Big Bang, Einstein's refusal to accept QM, and Ernst Mach's refusal to accept the existence of atoms.
I would suggest that you at least keep an open mind on the topic.
His work was foundational for the theory. However his later contributions to it was mostly detailed critiques. The critiques were brilliant and proved critical in shaping our understanding of the theory. (Even though Einstein wound up losing over and over again.)
There's really nothing like a determined and intelligent debate opponent for honing your arguments, and Einstein was immensely valuable in that regard.
Similarly, when Scalia died Ginsburg said she would miss his rebuttals to her opinions because they always made her final product better.
Considering how much things changed in the 20th century, I doubt the quote.
How many scientific revolutions did Einstein live through? Two?