It's partially American fear-conditioning to protect against subversive ideas, but it's mostly about ideology. Nobody likes it when you preach at them or try to convert them, regardless of what you're talking about. When the conversation is about "anarchism" it becomes a debate about the merits or shortcomings of anarchism as an abstract concept. It ceases to be about actual humans and their desires. The discussion almost inevitably deteriorates into an argument about hypothetical examples and counter-examples about why it would or wouldn't "work."

Instead, I've found that much more pleasant and effective communication comes from a genuine dialog - a mutual sharing of feelings and ideas - about the things we both care about. Nobody likes being told what to do. Whether or not you call that instinctive, human rebellion against authority anarchism or not is irrelevant.