It’s always important to ask why and look for the data yourself.

Look at all the wives tales in the past that were semi-effective just because of placebo effects or like you say implementing a health measure (even if it is not directly effective) normally means you have better hygiene anyways.

The problem with flossing is that it is so easy to do wrong which is why only professional flossing has significant effects.

It’s worth people knowing that unless they are flossing on a professional level they aren’t necessarily doing anything to benefit themselves beyond what a mouth rinse would do.