I don't think it's anyone's job.So do thier job? See what I mean? You want people to come, you want people to get involved.. you want people to participate.
Every committee or board I have ever been on has some sort of welcoming or at least an acknowledgement that you joined something. #### you even get a certificate from the Chamber of Commerce and are mentioned in their blog.
Everyone is a volunteer. No one is responsible. You have to really be a self starter.
So I think it's a combined problem of perception and communication.