That's the problem actually. It's so strong that it makes it more difficult for the principle to be applied for what is less strong. Also in some place it has also been overused to the point it's not effective because you don't know if the people accused are really nazi or not (in my country even left politicians may be called literal fascists by others at the left)
The percentage of people who are called Nazis who are actually them is probably higher than you realize, because the word "Nazi" makes people think of concentration camps, and we don't see those, even though the Nazis did over a decade of other bad stuff before that. A Nazi accusation isn't saying someone runs a concentration camp - it's saying when there are concentration camps, they probably will.
In short, the problem with using Nazi's as a comparison is the strong emotional reactions people are prone to experience. (Justifiably so to be clear)
When a person invokes the Nazi's while discussing subjects that aren't nearly as heavy (emotionally speaking) the horrors of everything Nazi related, they're leave themselves open to being perceived as hyperbolic. No matter how strongly one might feel about open source, the subject matter is just simply on a different emotional level than all the horror which is Nazi. (and therefore, ought not to used as a comparison)
And again just to be clear, I'm not accusing you of being hyperbolic personally, I just want to elaborate on why some people groan when they see Nazi's beings inserted into topics which they have nothing to do with.
That's the problem actually. It's so strong that it makes it more difficult for the principle to be applied for what is less strong. Also in some place it has also been overused to the point it's not effective because you don't know if the people accused are really nazi or not (in my country even left politicians may be called literal fascists by others at the left)