Why flossing is uncommon?

Why flossing is not generally mentioned in dental hygiene. This should be mandatory to do like brushing teeth with a toothpaste and tongue scrapping. I have never seen an ad on flossing. RANT I have this peculiar habit that I observe people's teeth like whenever I talk to someone.I've been single for such a long time and recently a guy approached me and guess what I met him and the first thing I noticed was his chipped tooth. And he is conventionally attractive like many girls have approached him.So the thing is that the teeth really matters to me but I thought in my mind that I'm I this superficial? So I continued talking to him. Now some days passed I met him again and this time I observed his teeth. And I saw a big chunk of tartar in his front side of lower teeth( lower incisor)😐 And that guy said to me in a phone call that don't you feel like kissing me? And I said , mere side se to 0% hai because I can't say that directly to him. Duckk I was in the talking stage and trying to look forward but I got turn off by that 🥲 Anyway I got to know his bad intentions so I'm not feeling guilty.