I postulate that the Wikipedia-editor experience was designed by the Creators of Wikipedia to be an unique type of Role-Playing game.
The concept is simple: instead of being payed, those who add to the sites are receiving the reward of recognition. There are myriad methods of "Levelling up", gaining EXP, joining parties. The reward of human-interaction pre-existed within online RPG and was extended/adapted into Wiki. There are bands of "fierce defenders" (those who hide behind the wall of certain pages, ready to instantly revert edits to their original healthy states). There are "barbarians" who anonymously come to ravage various concepts and authors. So Wiki-genre is the child of RPG & the child of encyclopoedia.
And the reason so many folks are willing to be contributors to an encyclopoedia without payment for services is because the Lore of the RPG, and all the pleasures that therewith accompany this have served as an effective substitute.
Is this also true for some discussion groups.