I think HN’s ‘smart’ code to remove clickbait fragments from titles didn’t help here. The page’s full title is

This Wikipedia of Algebraic Geometry Will Forever Be Incomplete. That’s the Point.

That “This”, IMO, makes it clear that they use Wikipedia in a genericized way (https://en.wikipedia.org/wiki/Generic_trademark)

it's used in the sense of 'a wiki project which tries to act like an encyclopedia' unlike for example the wiki wiki web. a similar kind of wiki is scholarpedia.org.

the emphasis is on the encyclopedia part.

It's a bit like a Wiki, except with more centralised editorialship. Confusing title indeed.