In my years as a working man, I had to read and approve thousands of memoranda. And any staffer who wanted his/her work to see the light of day knew that "Comma Bob" did not accept the slovenly habit of failing to place a comma before the "and" in a series, as in "Three cheers for the red, white, and blue."
And here's a good illustration of why that was so:

Kudos to theweaselking for spotting this one.