I think that's mostly because it captures the Chatterbox nodelet. Searching Google for a username usually brought up a few shreds of Chatterbox conversations. Uh, like it does now, too. (It probably won't in future.) Just search for a username that often appears in the Chatterbox, and select to view the cached result.

I'm not sure what the line

# sorry, but misbehaved robots have ruined it for all of you.

means, exactly. I was hoping the person responsible for that line, or for the final decision to block indexing, would have put in his two cents here. Maybe he still will.