History simply isn't written by the "victors". Firstly, that doesn't even make sense outside of military histories, where it's patently untrue. Secondly, and more importantly, history is written by whomever happens to write and have their writings survive.

Thats the problem with history. Interpreting facts is tough especially when you understand that only a small portion of the important facts are known. In contrast to hard sciences there is often no definitive right or wrong. Some things are easy to establish as true, at least with a good degree of certainty, when did something happen? This is often easy to know. But why did it happen? We dont know the precise thoughts of important individuals. Its mostly educated guesses.

History suffers from another problem which many won't be acknowledging. Confirmation bias. Many Historians have some form of agenda which shows in their works.

A simple example.

David Glantz is one of the most well known historians in regards to the eastern front of world war 2. In one of his earlier books about Kursk he examined that battle of prokharovka. He came to several conclusions all about the good performance of soviet troops on tactical and operational scale. The thing is he based his reports on the works of an involved Soviet general ( Rotmistrov if i remember correctly ) and these reports turned out to be pure fiction. He made the mistake to not check German sources. Glantz account of the battle was straight up rubbish. Later Glantz published another book about Kursk, when i read it i noticed he revised the battle and used sources from both sides and left out the descredited works he used before. Now the Battle was a disaster on the tactical scale . He didn't put it that blunt but there was no way around it. Suprisingly his conclusion of the battle stayed the same. Sadly his entire account of the overall Battle of Kursk was highly influenced by this climatic Battle on the southern front. He had his mind made up before he got facts, it just didn't matter. And when you write history you get away with it because its so hard to falsify peoples opinions. Sometimes it even comes down to writing style. Having a good writing style is very important if you are an historian in a popular field. If you have a thesis in physics and you get contraticting informations and test results then your thesis is done in history its not. I rarely see historians who change their minds in later works.

Edit: After i wrote this i remembered that this Prokharovka incident not only made Glantz look bad. Another historian used this Battle to support his agenda. I guess it was Zaloga who tried to show that the Soviet tank units had the same performance as German tank troops. This statement in itself is hard to justify at all. But he took this Battle and the account of Rotmistrov who claimed 500 german tanks were destroyed for an comparable number of Soviet tanks. In reality German troops lost a handful of tanks and some 30 or so damaged. Soviet troops suffered about 500 losses on a single day in this battle. This Battle hardly qualifies as example for the quality of Soviet tank corps...

Appeal to authority

Its ridiculous how prevalent this is in discussions. This subreddit is a very good example of this, it doesn't matter how elaborate your post are. Your post is based on facts and correct premisses? Doesn't matter if not a historian who sold a lot of books said exactly what you said. Thats the contrast to other sciences. So many historians have contradicting opinions on subjects how can it be that we take what they have written as gospel. Quote a historian and your post got upgraded from "maybe true" to "extra true". Is really unsetteling to see this over and over.

Its a good question of yours i wonder why you got downvoted.