It was not only the FDA that stopped snake oil. A lot of it was also stopped by state licensure and medical school accreditation (see the Flexner Report), all of which happened in roughly the same era.

What I take from this is that AI code, biology, etc, will not announce itself. We will have to announce the human-produced content. Introductions are about to be ritualistic again. Queue humorous (but not really all that valid) counterpoint: https://www.youtube.com/watch?v=hoe24aSvLtw