In terms of communities where you can get the most qualified person on a topic to reply, I think Quora would also qualify, and to a limited extent, Twitter.
Quora really seemed nice until they started publish everything I did there. I also think they had a real name policy. (At least thats how I remember it.)
They might have fixed that now but I feel it would take quite some effort for them to make them feel safe again.
They might have fixed that now but I feel it would take quite some effort for them to make them feel safe again.