What's interesting is that there is no strong proof that flossing actually helps. The U.S. Health department had to take down their recommendation to floss because they couldn't produce evidence of its efficacy.
None of your sources are studies with a strong causal link between flossing and dental health. People who floss do have other good dental habits, so there's definitely a correlation that exists. And remember, I'm making no claims either way, I'm specifically stating the current scientific evidence. I personally floss.
Counter point: that's the stuff you're shoving deeper into your gum line. And to reiterate, I do floss. However, I can see potential issues with it that may counter its effectiveness.
Flossing IS important:
https://www.nidcr.nih.gov/health-info/gum-disease/ask-the-ex...
https://www.ada.org/resources/ada-library/oral-health-topics....
https://eclkc.ohs.acf.hhs.gov/oral-health/brush-oral-health/...