Have you never noticed that all the really good sites you 'find' have been because someone posted the link? For example in a comment on HN, or reddit. Or a related link on Wikipedia or the sidebar of a subreddit?
That to an extent, and also the fact that _real_ artificial intelligence - the kind that you could share exactly where you're up to with programming and it could tell you exactly what site to read next - that doesn't exist yet.
I once read that Google indexes 0.5% of everything publicly known.