They browsers could ban domains just as social media apps can ban people. They could literally add a “report” button to browser UI, hire a bunch of moderators,

They browsers could ban domains just as social media apps can ban people. They could literally add a “report” button to browser UI, hire a bunch of moderators, ban certain pages and do the exact same kind of moderation of the web as Facebook does on their site. What you propose is not a real distinction, it’s just description of how things turned out being.