HN is mostly young people who only associate with young people; if you can get past whatever vestigial respect for elders remains as a cultural value, most people will agree that old people are a pretty good source of ugly. Especially pre-modern medicine, ravages of outdoor labor and warfare... We arguably do live in a world where all 20 year old women are beautiful, and the 90 year old women are somewhat less so.

As you realized, beauty is relative (to ugliness). I can't quite grasp how you missed this relative aspect by going further with your assumption of "everyone is beautiful". People will always find distinctions and there always will be a scale of beauty (or whatever else).