No, there are entire businesses. Kim K for a well known example has a number of people who she pays to handle the posts ‘she’ makes. That’s part of her PR. In truth, half the posts are probably written by those same people posting as her. Nothing new or surprising there.
Point being, far more than one person can and does profit from social media posting. The consultants etc are the same people with a different job title making the same money. It just passes through different hands. The nature of the biz is the same.
OK, my point is that - using Kardashian as an example - Kardashian controls the message and reaps the rewards. There are no filters to the public that she can’t change instantly unlike radio and tv ad time booking or even doing a concert or pr speech.
Accordingly, the “message” can be controlled far more exactly than with traditional media outlets using traditional media experts. Not that the right advice wouldn’t go a long way.