Definitively agree. Being blunt, too direct is just the opposite of a good and effective communication.
It's a fact of life that people shut down when approached with evidence that refutes their world view or choices. It doesn't matter if it's your boss or grandparents.
I don't really agree with you. This is a basic quality of skilled leadership. You want people refuting your worldview with evidence! It lets you correct course and make things better.
Only insecure people shut down like this in my experience.