Another idea I might add to my original thought would be people's fear of change. I would guess that goes back to before the days of agriculture, where you had to move with your food source. Any change could be dire to you tribe's survival. Change in food source means learning new land, hunting techniques, poisonous plants, etc.

So I think that anyone challenging authority is also challenging the status quo and is seen as one that wants to bring about change. The primitive (lizard) brain cares about two things: survival and reproduction. Change threatened survival in the past, and that fear is still with us, causing us to condemn the changers. People who are in a position to prevent social change (like, say, a psychologist) will do anything in their power to feed that fear of change because they like the way things are. "Things right now are the way they are supposed to be," their lizard brain tells them. And so they close the minds of individuals who might have otherwise had a great impact on society.

What gets me is how people never learn. Socrates was condemned and executed for questioning religious and governmental authority. Soon after the Greeks regretted it and erected statues in his honor, yet that same mistake of casting out the independent minds is made every generation. Sad, really.