They are being too restrictive on what they define as a virtual community. For instance the forums in city-data.com has more than a million members. Same with bodybuilding.com

Keep in mind that having a million users on your site doesn't warrant it even meeting Wikipedia's notability threshold on its own.

You need to add "... Mentioned on Wikipedia" to the submitted title.

[Source: I used to work on one of the sites on this list, and its article went through AfD several times and it barely made it each time. It was never the number of users that saved it. Also it shows how stale this list is, because it shouldn't still be on there.]

While interesting, I don't think you can expect that list to be comprehensive or kept up to date. For example, Facebook (as of this writing) has 1.79B monthly active users[1], well over the 1B listed on that page. I also assume Yelp (not listed) has over 1M active users.

[1] http://newsroom.fb.com/company-info/

4chan? It is not there.