Comma Confusion

What is a serial comma? It is not a comma who goes around punctuating every innocent sentence fragment. Joking aside, everyone knows that we need to use a comma when listing items of three or more. The question is where do the commas go? Example: I love apples, oranges, and peaches. The comma after oranges and before peaches is called a serial comma. But why can't we just write: I love apples, oranges and peaches. Do we need the serial comma??? To relieve our frustrations I linked a helpful website to this blog, which explains style guides that support mandatory use of the serial comma, as well as style guides that oppose mandatory use of the serial comma. I hope this helps. P.S. Yes, APA/MLA/Chicago all support the serial comma.