What could be more fearful when you are in trouble and call out for help than the lack of sound that mimics the silence of the grave itself? Silence by way of response is a great technique for expressing things that you may find difficult to say — merely say nothing. You can always defend the innocence of silence.
However in specific silence you have the permission for every monstrous injustice ever done in the name of demented righteousness. Slavery, Nazism, misogyny, every instance of abuse, lynching, enabled by the silence of those who could have spoken up but didn’t. Silence also erases all hope of talking things through, clearing up bad feelings, making peace.
Silence, while sending a message very powerfully, takes no courage, no effort, nada. You just keep your lips sealed and let the silence of death have the perfectly defensible last word.
When you hear it offered as the last word, understand the moral cowardice at work and trouble yourself no longer with the imposer of silence.