I completely agree with you re: Tumblr and it's complete fail at conversation. To be honest, I didn't even know that this comm existed until today when it showed up on my LJ homepage. I've just always assumed that CM fans were quieter than most.

I don't watch the episodes live so I'm always a week or so behind. Perhaps that doesn't help move the fan conversation along... since everyone is onto the latest thing while I'm still marinating in the past ;)