Jesus needed promoters or forerunners to spread his message before he made his rounds in the same vicinities. Their task was to make Jesus known.
They were to do this in two ways:
1) Heal the sick - This was an important way of getting people's attention, winning people's hearts and creating real anticipation of his coming. If the forerunners or promoters were that good, what about Jesus himself?
2) Second, they were to announce that the King is coming - Not only was he coming he was