Phree says:

Actually if you look inside any album cover or read the credits most track say written by so and so meaning when its a crew or atleast 2 people the person who always sounds better will spit while the the other writes. this goes back to the early days of rhymin actually.

grab up any cd or tape and look ad the tracks and see, I bet you it will say written by blah blah and so and so and most of the time that just for one rapper on a single track not even a crew.