The study of history is done by many, many different people over many, many centuries. It would be illogical to say that just because some make a certain mistake, all do.

Additionally, you cannot say nothing changes when the understanding of history constantly changes, as our archeological abilities steadily improve.

Lastly, even scientists need to fill in blanks sometimes. Einstein was rather famous for filling in some critical blanks in Newtonian physics, for instance.