Why Weak or Blocked URLs Fail to Enter Google's Index
https://therankinglog.juniperbrief.com/posts/why-weak-or-blocked-urls-fail-to-enter-google-s-index
When Google's crawlers try to access a URL and get a server timeout, a 404 error, or a redirect loop, they just give up and move on. Weak URLs often lack valuable content or have thin text, making them low priority for indexing. Meanwhile, blocked URLs with a 'noindex' tag or a robots.txt disallow directive are explicitly told to stay out of Google's index, no matter how good they are.