I won’t dispute that fanboyism is thing, but also I don’t think many evangelists as it were view Linux as a “silver bullet”, just as the most ethical option given the alternatives. And they feel very strong feelings about this, that come across as Weird and Scary to people not used to seeing software treated with the same enthusiasm as politics.
Also, I should add that many view open source software as having the potential to one day be the “silver bullet” in a way commercial software can never be due to it’s structure.