2- the achievements of real people are sometimes controversial. Who could say with certainty that Cooley and Tukey invented the FFT, while it was used by Gauss in his astronomy work to speed up his calculation, but thought it unimportant enough to report compared to his number theory work? That itself may be controversial. Science is littered with misappropriated credit. For instance George Dantzig did not invent the first solution the the LP problem. Fourier knew about it ; people in the Soviet Union were using it before WWII. Hence writing about real people, particularly scientists, is hard.