Why is the rotation system used in volleyball?

Whenever your team wins a point on the other team's serve, your team gets to serve again. Before your team serves, it rotates in a clockwise direction: right back, the server, becomes middle back; right front becomes right back, now the server; middle front becomes right front; left front becomes middle front; left back becomes left front; and middle back becomes left back. Your team won't rotate again until there is another side-out, if your team again wins a point on the other team's serve.

explanation:

two years ago, when picking flowers in the mountains back of yosemite valley, i found a book. it was blotted and storm-beaten; all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however; many of the inner pages were well preserved. and although all were more or less stained and torn, whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today; its granite pages have been torn and blurred by the same storms that wasted the castaway book.two years ago, when picking flowers in the mountains back of yosemite valley; i found a book. it was blotted and storm-beaten, all of its outer pages were mealy and crumbly. the paper seemed to dissolve like the snow beneath which it had been buried, however, many of the inner pages were well preserved. and although all were more or less stained and torn; whole chapters were easily readable. this is the condition of the great open book of yosemite glaciers today, its granite pages have been torn and blurred by the same storms that wasted the castaway book.