His finalized paper on General Relativity had very few references too, and while Riemann geometry is currently widely known by physicists it wasn't then. Indeed Einstein did not know it until a friend taught it to him.Citations are for bringing to the readers' attention supporting work that they might otherwise be unaware of, for supporting unusual claims of fact, and for demonstrating reasonable familiarity with the state of the art. If, as I expect, you are referring to the 1905 "On the electrodynamics of moving bodies" Einstein started from a base of generally accepted science that was already completely familiar to his intended audience. .
Einstein did not even cite Riemann!
I think if you were to look at Einstein's papers you would find that he just did not cite many references...the "sure sign" according to certain people, that he was a kook.
Also, you gave two reasons for citations--First that citations provide valuable information, and second that they demonstrate that the author demonstrates reasonable familiarity with the field. I find your second reason to be very troubling.