New colonies were springing up all over New England. The Massachusetts Bay Company needed to keep an eye open to keep up its own legitimacy and legal patients. There was always someone bending the ear of the king. If one Puritan community didn’t agree with your beliefs, one could move to a different one, this included preachers.
below map from “The Beginnings of New England or the Puritan Theocracy in its Relations to Civil and Religious Liberty by John Fiske (1897)