Earlier quoted context omitted.
IIRC there were studies saying that flossing isn't as great as people suppose it is. My completely uneducated guess is that it's marginally useful for people with good teeth (shape, spacing) because debris doesn't accumulate as easily, and brushes are effective. For my case (crooked teeth, very narrow gaps) it's a great helper to get out the debris, morsels of food etc. that the brush can't get out.
I shared this with HN on many occasions. My wife has crowded teeth, doesn't floss, barely touches her waterpik, doesn't use any proper brushing technique. She probably had a couple of fillings done since I met her 20 years ago. In the meantime I have cavities almost every year, one root canal and a dental implant on a previosly failed root canal. I flossed since university and use mouth rinses and electric toothbrush…
My wife and I have an almost identical routine and diet, we use the same brand electric brushes, always twice a day, and usually have coffee together. However, she's not had many dental problems, but I've had to go to the dentist tons this year. Oh, incidentally I also knocked my front teeth out in a cycling accident.