Side note: Something weird just happened. I put this comment in here, and suddenly, "Deleted Page" cluster appeared. But I'm NOT throwing anything into the trash. Please don't get mad at me..! -- LionKimbro
Hmm, yes, I think the two are related. First, does CarryingCapacity refer to the number of parcipants, or the number of topics, or a combination? I always thought it was a combination. Second, I think that wikis can be over the SmallGroupDiscussionSizeLimit and yet under their CarryingCapacity. In other words, I think wikis, even without enhancements such as NearLinks or FilteredRecentChanges, can accomodate more participants than a "small group" can.
I theorize that the most important factor is that discussion is segregated onto many different wiki pages. Imagine that a wiki had to have only one page; maybe then the SmallGroupDiscussionSizeLimit would be equal to the maximum allowed number of wiki participants. The transition from a one-page wiki to a conventional wiki would be an application of EnlargeSpace.
This is an aspect of a more general problem; CommunityMayNotScale.