That's such twisted logic. Are you saying I'm doing unpaid work for my social group when we have a conversation? Jesus Christ not everything needs a dollar symbol attached even if it benefits a company.
I think that was the point - that answering questions on SO is like having a conversation, and feels pleasant to some people, not like work.
At least it feels pleasant until a moderator or community manager starts interfering with it.
The ratio of value (or entertainment) provided to oneself versus value provided to another entity clearly differs significantly between a user of a site and an (unpaid) moderator of it.