This post uses phrases such as, "the voice behind a brand or organization" and "link between community manager and brand reputation." It doesn't address representing or advocating.
It does declare that community managers link. They are a bridge between brands and the public. The post describes roles, as that link, that they might have to play: "nurse, teacher, police officer, helpful neighbor, mail carrier or ambulance driver." To help explain, I'll offer some examples, here:
Soothing a customer's dissatisfaction = nurse.
Offering a how-to tip = teacher.
Moderating comments or deleting posts with personal attacks or that are wildly inappropriate = police officer.
Offering a link to a video or post that answers a customer's question in more detail = helpful neighbor.
Relaying the customer's issue to precisely the right person for an answer = mail carrier.
Knowing when a problem is urgent and dealing with it in that way = ambulance driver. Perfect example: Tweets sent during the 2013 NCAA Championship Game. Here's a link to the exchange with our satellite provider. It's worth a look.
A community manager's main responsibility is to be the go-between. Done well, it feeds useful information about customers, service, products, etc. back to the brand. But, it also helps keep customers satisfied, gives them a voice and lets them reach a human contact.
Bottom line: There's no need to rank who comes first -- it's not a competition. Being an advocate of one group or another is an entirely different thing than being a skilled community manager.