Resume?

On a lot of the common app supplements (Dartmouth, USC) it gives you a space to attach a resume. I don’t feel as though much new insight would be gained by me attaching a resume; it would just give me a few extra spaces to include less-than-useful extracurriculars that I had to leave off the common app (NHS and CSF treasurer, the club I founded that didn’t do that much, a 6-hour-a-week tutoring business). What exactly is the purpose of including an additional resume, and is it necessary or considered beneficial?