I used to believe this but I don't think so any longer after enough time on the internet.

There's probably not more than 50k meaningfully unique sites with some notable amount of actual desirable information, after excluding all the SEO'ed sites, blogs repeating each other, etc... at least for the English web.

Manual curation is entirely possible since probably there aren't even 50 such sites being created per day on average. This is including every single forum still open to public viewing. There really aren't that many left (<10k).