History is very "tricky" science.
There is always a bit of propaganda involved in, I believe every in nation history. But despite that, the biggest problem for such far history are Sources. Many books/libraries are destroyed, sometimes scientists don't agree if they should take national "poetry" as valid source, some nations even didn't have book at all until quite recently, etc.
Also another problem is "selectivity". Some "scientists" (intentionally or not) ignored sources that doesn't fit their government ideology or goals.
Some scientist have valid sources and write what they read indeed, but they miss Context. To understand entire context across different epochs, you need big bran and big knowledge.
Etc.
So we should not believe there is "central authority" for History. There is no simple truth. There are many layers of truth.
So yeah, I agree it's poor when someone is ironic and believe his perspective or his sources are the only valid.