There doesn't need to be a team. Individuals can act according to personal incentives and still create coordinated behavior. Look at flocks of birds. Each bird acts for itself; together they move in unison.
Usually when I read "astroturfed" I assume there's some higher level coordination involved. I think the flock of birds metaphor is probably a reasonable comparison to the behavior we see on social media all the time - members acting individually on their own self interests in a means which appears coordinated when you zoom out.
