In other words, knowing what a genre is used for can help people to accomplish goals, whether that goal be getting a job by knowing how to write a stellar resume, winning a person’s heart by writing a roman-tic love letter, or getting into college by writing an effective personal statement.
This can also be limiting for example, if a person was to make a song and some one's interpretation deemed that it belongs in the "Hip Hop" category, that would exclude it from other categories.