Since that happens to be just a list of individual usernames, in that specific case the Oxford Comma doesn't serve any purpose and as per any major English vocabulary it's up to the writer to use it or not. Yes, I googled it.
without the comma, the last two are together, like a couple. which is ok, in a few cases....
also have an issue with the orgy version. a, b, c and 6 others.
i don't think it is getting much priority, since i haven't connected the forum login to the wiki, so we can get that to work correctly