There are 10 possible criteria from which to pick one that a nominated site satisfies, including the "masterpiece" criterion (i). 4 of them apply specifically to natural sites, such as the reef, while the other 6 are culturally-oriented.
The "masterpiece" criterion is criterion (i), although you could arguably make a case for Wikipedia under criteria (iv) or (vi) as well (emphasis mine):
(iv) "is an outstanding example of a type of building, architectural, or technological ensemble or landscape which illustrates a significant stage in human history"
(as a global-scale collaborative project with millions of participants in the information age)
(vi) "is directly or tangibly associated with events or living traditions, with ideas, or with beliefs, with artistic and literary works of outstanding universal significance"
(free and open dissemination of information)