I was looking at Ciril Hirtz' excellent video on shaping baguettes and stumbled across this "Expert Village" video showing the "cut and pull" technique for shaping a baguette. It is so bad it's funny. There are several other videos by this same fellow taking one through the entire process. In one he explains that steam is used "because the moisture from the water kind of vaporizes and soaks up inside the bread giving it that nice pillowy softness inside."
The "cut and pull" technique for making an "authentic French baguette bread"