What does Hawthorne gain by including the names of actual persons and places?
Authors, such as Nathaniel Hawthorne in "Young Goodman Brown", tend to use names of actual people and places for one main reason.
The main reason which authors tend to do this is to allow readers to apply any prior knowledge to their reading. What this does is allows a reader to bring prior knowledge to a reading so as to more readily engage in the reading or bring memories forward so as to help them to connect new information to the current reading.
Also, this information allows readers to more readily understand the historical aspects, dialects, ideologies, and culture of the setting used in the text. For example, if reading a text placed in the South, one would expect to read dialogues which depict a specific slang typically used in the area.
This use of actual people and places helps readers to understand what is happening in the community/society which would lead to development of theme or ideologies examined.