Example 1
Portland is home to dozens of gourmet corn dog carts; there are several in the Pearl District alone.
Using the indefinite pronoun several here indicates that it isn't important for the reader to know precisely how many fancy corn dogs stands there are.
Example 2
Nobody should ever sing "Bohemian Rhapsody" at karaoke.
It's appropriate to use nobody here because it doesn't matter who the singer is; they'll never be as cool as Freddie Mercury.