Back in the infancy of the Internet, I got ordained as a minister online. Really funny, haha. Later on, some friends wanted to get married and I volunteered. To my great surprise, they accepted. Holy shit! Suddenly I was worried that my being a fake minister my cost someone their marriage. So I called the WA State Dept. of Licensing and asked what credentials you need to perform a marriage in WA state. They said (and I'm paraphrasing) "You gotta be 18, but other than that, we don't actually give shit about your credentials as long as you pay the money."
The judge who performed my wife and my wedding related an interesting story. He had performed a ceremony for a young couple. A couple days later, they decided it was off but they had yet to file their paperwork. Question: Is the marriage valid? Good question, right? The judge didn't know, so he queried his fellow judges online. He concluded that the answer was yes, they were legally married. The reason is that the concept of civil marriage goes all the way to back to English common law, and if you say "I do" you are entering into a legal contract. Verbal agreements are legally binding, and therefore those two idiot kids were legally married. Filing the paperwork means there is a record of the contract, but the contract starts when you say "I do."
So to me it makes sense you don't legally need an officiant, depending on the state of course. I know in Alaska _anybody_ can be an officiant. No requirements at all. In WA State you have to a judge or an "ordained" minister, but they don't ask for documentation. Which, IMO, they shouldn't.