The same way test pattern and elevator music substitute
when services are down.
Not really. For the most part, humans tend to view themselves at least
partially in terms of memberships of groups. Some people are dominated
by this; look at Kenny's obsession with "regs". Very few people, though,
don't have at least some sense of "I know these people and ought to act
in ways compatible with their well-being". In general, a community which
rejects any kind of personal chatter will be unhealthy, because people
won't view themselves as personally engaged with the community, and they
won't have any particular desire to support the community or its members.
In short, for an interactive discussion medium, the most effective way to
have a healthy culture in which people can communicate effectively and keep
the community's discussions topical, is to allow certain *kinds* of
digressions or chatter, because they form what is essentially a carrier for
the signal. Take away the carrier, and you lose the signal.
-s