Dental caries result from certain species (S. mutans et al) of bacteria digesting sugars into acids that chemically erode bioapatite. If you destroy the bacteria, such as by using mouthwash, or prevent them from adhering to the teeth, such as by using xylitol, or deprive them of sustenance, such as by not eating sugars or simple carbohydrates, you won't get cavities, and you won't need to worry about flossing--
to prevent cavities.
But cavities are not the only problem you can have in your mouth.
Food particles left in the mouth for long periods can cause an inflammatory response in the gums. This can lead to bone loss in the jaw. And that can cause your cavity-free teeth to fall out.
Flossing through the space between tooth and gum can potentially remove such particles, which would help prevent gum disease. But it might not be necessary to do it every day. Once a week, maybe? After eating jerky or popcorn?
I have no idea how often it is necessary to floss to achieve a statistically significant reduction in any of the oral diseases, or how much of a difference there may be between flossing twice a day and flossing once a month.
My dentist recommends flossing whenever I brush. While the recommendation to floss is probably well supported, I suspect that the frequency may be more based on psychology than anything else. They just attach it to the brushing habit. Perhaps it would be better to attach it to "whenever you trim your fingernails", or "whenever you shave your legs", even though those are not related to oral hygiene.