You don’t seem to get my point. For a platform to let me reliably filter a whole topic, the majority of posts need to be tagged with that topic first. Reddit/Facebook don’t do that, they have communities and loose categories, not consistent topic tags across all posts. Twitter only partially does it with hashtags, and hashtags are neither comprehensive nor applied consistently. I’m talking about platform-level, booru-style or collaborative tagging so blocking a tag actually removes the tagged content without me having to unsubscribe from dozens of communities or build giant keyword lists.