I don't quite understand why this question has gotten 2 downvotes shortly after I asked it. According to the help center, plot explanation questions are on topic. And this is plot explanation: why does the history of the game differ from established history? In case it's another reason, I'm perfectly willing to rewrite it.
Note that I have not downvoted your question, and I do not intend to do so. However, I can understand why someone might.
Your question deals with something that is explained normally via the plot. I would assume that people who have played and beaten the game thought this was a "poorly researched" question. I think this enters a grey area where certain players might have a question that they're legitimately curious about before the game bothers to explain something (e.g., "Hey, who is this Darth Vader guy anyway?"). In this kind of situation I think the question itself is perfectly valid (as yours is), and in my opinion an ideal answer would look like this:
This is explained during the mission "They tell you about the Nazis". The specific reason is: Some sort of spoiler tagged summary.
Down votes are not close votes.
If your question was off topic, people would be voting to close your question. Nobody has.
Instead they have downvoted your question, meaning they believe it is of low quality or not useful. This is an opinion, to which they are entitled, and to which you are entitled to disagree. However, complaining about it is generally considered unbecoming.