spare the group from scale
See, this is something that's been nagging at my mind lately. Simple logic would dictate that easier distribution of information (which encompasses both sharing of resources and social interaction in one big honkin' swoop) would allow a monolithic organization to stay more monolithic, that it could communicate more effectively, that it could act more swiftly as a unit, etc.
The result is otherwise, and I think the reason has to do with people not being smart enough to know the best plan. Short version, although everybody can cooperate in a way that is most effective to them as a group, they do not.
You get a group that's too large, it splinters, becomes topheavy, becomes sluggish, etc., because as it encompasses more and more humans, it has a greatly expanding range of motives driving their involvement. Eventually, a small subset of them may locate common interests and remove themselves from the larger group (i.e., the small research consortium composed of a handful of researchers from some huge corporate R&D division) or if enough of the individuals have goals completely counter to the prime goal, then it's possible that their actions, due to chaotic "magnification", could crowd out the attempts on the part of the "group" to persevere. (My understanding is that this is what happened to Webvan, in a way. Statements from employees indicated that a significant portion of the employees did not want to perform at their jobs. In a world where pizza delivery is approaching perfection, not delivering something is akin to kicking the customer in the ass. Word-of-mouth coupled with a significant portion of non-functional employees could destroy a company easily, IMHO.)
So it's interesting to note that a focused goal, as long as it excludes most people, is possible to achieve. Apparently being a successful community is, in part, knowing who to alienate.
You are what you think.