There's a fair bit of truth to this, but it does leave out the fairly substantial number of faculty who teach in undergraduate or Masters-level institutions. I teach physics at a small liberal arts college so I never train grad students myself, but I definitely needed a Ph.D. to get this position.

That said, even if there were just as many of us as there are faculty at Ph.D. institutions, that would only raise your number who get tenured positions to 2.