This idea is blown out of proportion especially by those who have no idea how History is written and just run off with that idea. It implies that History is written in stone which it is not. It is written by historians who base their writing on sources. Now these sources can be biased, they incorrect and they can be incomplete. This is why it's so important to pay attention to the sources and citation.
Historians can also only base their writings on the sources that are available. WW2 is an excellent. The three primary sources of WW2 for the longest time, the sources that shaped our understanding of the war were British sources, American sources and German sources. That's right, German. The losers views shaped our understanding. The reason why is because historians could access them. The Soviets on the other hand restricted access. They wanted to control the narrative of the Great Patriotic War so it wasn't until the collapse of the USSR that we could gain assess to their archives, memorials and sites.
The victors certainly do influence the initial writings, there is a narrative but again, History is not static. For gods sake there is an entire school of History, Historiography, which is dedicated to studying how History is written. History is always changing with new ideas and new evidence. Just look at Verdun for so long we were told Falkenhay's plan was to bleed the French dry but in recent years with emerging evidence it may simply have been fabricated to justify a failed strategy.
We are always learning when it comes History and that's why it's so fascinating