Nonverbal communication is important to signal to others our inner thoughts.
What happens when we attempt to express "neutrality"? Is a face devoid of emotional expression neutral? Or do people perceive something else. If curious, try a (consensual) experiment and have someone talk to you while you relax your face. Then, switch places.
Primitive humans were tribal and faces were incredibly important sources of expression for understanding one another. Researchers observed that we make assumptions about people based on their facial expressions to better understand our intentions, trustworthiness, and likability. Ever wonder why people don’t respond positively to our “neutral” facial expression? Watch this video to see how we are "wired" at birth to make meaning of "neutral".