Or is that just a secondary benefit?
There are many levels of spiritual evolution. I believe each spirit writer is supporting a revolution in any one person at any given time. The purpose is not to improve the world, but to provide the crumbs needed for the ones who are in the stage of development that the writer is helping to promote.
So, for example, I represent information for those who are ready for an awareness that death is not real. Or I represent a message for those who believe there is going to be a reckoning that we must be ready for. This reckoning may happen in our lifetime or may not, but it represents the summation of what God will bring to humanity if it doesn't stop causing backward evolution on the earth.
Each messenger is granted a message that is relevant to those who are getting the same message. That same message is reinforced when they read from others the messages that they are given. It doesn't improve society but changes it. It causes a shift in the way we think.
My hope is to help the shift toward seeing ourselves the way God sees us; as beings of natural construction not beings of unnatural construction. If we see ourselves as natural servants then we may see ourselves in nature the way the ancient ones used to see the human race. They who saw nature in this way survived the death of their fellow man. Because they secured themselves a spot when man over ran the cycles of nature that could no longer sustain him.