Core Web Vitals matter, but they're one ranking signal among many, and for most small-to-midsize sites, a mediocre-but-passing score rarely explains a visibility problem on its own. Indexation issues do. Pages that exist, have decent content, and simply aren't in Google's index at all because of a crawl block, a canonical pointing elsewhere, or a sitemap that was never updated will never rank, regardless of how fast they load.