Anything online with a community can be considered an MMO if you play it correctly. That might sound like a joke (due to it being a joke), but consider that even Wikipedia itself can be considered an MMO in the right light. Players (editors) choose a race (editing style) and class (editing role) and roam over a vast landscape (article database), exploring both hidden spaces (orphaned articles) and well-known boss areas (featured articles). And you get experience (edit count) for playing (editing articles)!
If all of this sounds exceptionally silly, that’s because it is; the article in question is meant to be absurd and is more of a parody of Wikipedia editing culture than anything else. One could argue that a point is being made for the power of framing actions and what people are doing in a particular game, but at the end of the day it’s just some tongue-in-cheek observations about editing Wikipedia. But please, don’t take this as an indication you should go over there and grind.