People seem to be adding comments to MetaFilter at a fixed rate rather than proportional to the rate of user accretion.

As one comment has it : I wonder if there's kind of an organic limit where people feel like a thread is 'full enough' and don't bother joining in the conversation...

See also :

  • Wonder what would happen on TypedThreadedDiscussion? Would the extra organization encourage more comments (because you feel less overwhelmed) or fewer (because it's easier not to repeat what's already said)