Yes, seeing each other's face is part of communications, but it's not compulsory, nor should it be. Like most things in our society, it's a matter of freedom of choice. We manage to communicate just fine sitting beside each other,  or in the dark. This compulsory 'must see the other person's face' thing is sheer bullshit, and an excuse for bigots and misogynists to support the oppression of a small group of Muslim women.