Just thought I'd pass along this little tidbit https://www.washingtonpost.com/news/volokh-conspiracy/wp/2017/03/15/a-b-or-c-vs-a-b-or-c-the-serial-comma-and-the-law/?utm_term=.09e8c9ffe738
Good article. IMHO, the Oxford comma is not a requirement in writing, but can be a useful tool for clarity, as the article shows. Consider this sentence: At the reception, I met Robin, her husband and her editor. The writer could be talking about one person, two people, or three people. A simple comma resolves the ambiguity. At the reception, I met Robin, her husband, and her editor. (Remember that Robin could be either a male or female name.)
It's not always strictly necessary for clarity, but I use it regardless because it is easy to use and even when I don't see an ambiguity others may.
Some people are stylistically opposed to anything that is not absolutely necessary, seeing it as clutter even if it has a possible purpose for clarity. It's an interesting and usually internally consistent stylistic philosophy. It just doesn't work for me. (Those people would, for example, have reacted to the "that is" in my sentence above with a shudder.)