If the phrase is clear and not likely to be confused then it is optional, which means use it if you want and tell anyone whose sez you don't need it to perform an unnatural act on themselves unless you are following the Oxford style guide, in which case don't use it except to avoid ambiguity.
So it is a matter of style
For example, my love of certain fruits and veg could be equally expressed as apples, pears, and carrots or apples, pears and carrots because (and assume this is true) that 'pears and carrots' is not a thing. If pears and carrots is actually a dish, then that comma before the and in the sample phrase completely changes the meaning -- from listing two things to listing three things.
Refer your style guide specified for whom your work is being written for.
Which means if it's your book or short story and the publisher doesn't specify a style guide for submissions, do what you want. For fiction, I don't think it's a big deal either way. Publishers will edit the piece to fit their standards before publication.
The only people that I've observed it mattering to people in critique groups that can't think of better feedback to give me on my writing. When they are critiquing my format then I know I've exceeded their ability to provide me with useful insight to my work.