“‘As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches 1.’ In other words, Godwin observed that, given enough time, in any online discussion-regardless of topic or scope-someone inevitably makes a comparison to Hitler and the Nazis.” Wikipedia
I have not bothered to check this out. It is not that important. But assuming that Godwin’s Law is indeed valid, there are three reasons for invoking Hitler or Nazi analogies.
First, someone loses control, gets angry and insults someone else. Usually there is no good reason anyone else can see for this insult. Just mentioning Godwin’s law might deter this kind of reaction from an angry person. Everyone except the person hurling the insult understands this to be wrong.
Second, someone claims that there is no right or wrong. This should be rare, but sadly it is all too common. Hitler or the Nazi party is invoked because Hitler and the Nazi party are universally understood to be evil. It does not matter that Mao Tse Tung, Joseph Stalin and others were far more evil. It is the concept of evil which is universally understood to be embodied in Hitler and the Nazi party. This is the sad reality when people abandon any kind of moral standards. These are the people who angrily shout; “Who are you to tell me what to do!” Personally, I know of no other way to deal with these kind of people except invoke Hitler and the Nazi party. If anyone has a better idea, I am open to suggestions.
Third is the Nazi propaganda technique of the Big Lie described by Adolph Hitler in Mein Kamp. That is, people will not fall for a simple lie. They can see through it too easily. Tell a big lie and keep repeating it. This concept of the Big Lie is the primary propaganda tool of progressives (the left) in this country. It is used because it is effective. It is also difficult to overcome. Once again, the only way I know of to deal with The Big Lie is to point out that what someone is saying is not true. Mentioning that this is a Nazi propaganda tool is usually not very effective, but it might work with some people.
Anyone who has a better idea about two and three, we welcome your comments.
FINDLEY FAMILY VIDEO 
The big lie works because we are too lazy to check it out and if we do find it to be lie, we are intimidated when we speak up.
thank you Onisha Ellis