There absolutely is a reason for it. My marketing department wants to place product "call to action" snippets in the middle of pages that are informative in nature. They usually come up with 5 to 10 pages of half-educational, half-infomercial type spam and want to give the customer that opportunity to add the product to the cart on every page of the webfomercial (my word, coined here ;-P)

On these pages, the designers want to test as many as 5 different presentations of the product. The only common elements of the product buy they need are the price, quantity, attributs and the actual add_to_cart button.

Does this make sense?

By the way, in practice, I have found that this works okay, not great, for anonymous users but it does not work for authenticated users because of the need for a form-token.