I am highly skeptical. In my younger years, I brushed regularly but did not floss at all. After dealing with a surprising number of cavities over a short period of time, I decided to just start flossing, morning and night.

Not only does flossing remove quite a bit of, er... stuff... that toothbrushing does not seem to get, I have not had a single new cavity in 25 years. The only issues I've had were old fillings falling out, including one that cracked my tooth which required a crown. Not a lot of work considering the time span.

Obviously one person is not "data" but seeing as I am that one person, I'm going to keep flossing.